From 53f91ef0ea7d588a26e90bf87ad46bdb84938d6f Mon Sep 17 00:00:00 2001
From: Marc Cromme <marc@indexdata.dk>
Date: Mon, 12 Jun 2006 09:39:17 +0000
Subject: [PATCH] removed non-functional ZVrank algorithm for ever. Removed
 description in documentation.

---
 doc/Makefile.am        |    4 +-
 doc/administration.xml |    7 +-
 doc/zvrank.txt         |  207 ------------
 index/Makefile.am      |    6 +-
 index/zebraapi.c       |    3 +-
 index/zvrank.c         |  852 ------------------------------------------------
 6 files changed, 9 insertions(+), 1070 deletions(-)
 delete mode 100644 doc/zvrank.txt
 delete mode 100644 index/zvrank.c

diff --git a/doc/Makefile.am b/doc/Makefile.am
index 8aa5487..d088bdf 100644
--- a/doc/Makefile.am
+++ b/doc/Makefile.am
@@ -1,4 +1,4 @@
-## $Id: Makefile.am,v 1.46 2006-05-30 23:08:29 adam Exp $
+## $Id: Makefile.am,v 1.47 2006-06-12 09:39:17 marc Exp $
 docdir=$(datadir)/doc/@PACKAGE@
 
 SUBDIRS = common
@@ -78,7 +78,7 @@ man_MANS = $(MANFILES)
 
 EXTRA_DIST = $(XMLFILES) $(REFFILES) \
 	$(doc_DATA) $(EPSFILES) $(man_MANS) $(REFFILES) \
-	zvrank.txt marc_indexing.xml entities.ent local.ent.in
+	marc_indexing.xml entities.ent local.ent.in
 
 zebraidx.1: zebraidx-man.xml zebraidx-options.xml zebraidx-commands.xml
 	$(MAN_COMPILE) $(srcdir)/zebraidx-man.xml
diff --git a/doc/administration.xml b/doc/administration.xml
index 01e8f22..de01bd5 100644
--- a/doc/administration.xml
+++ b/doc/administration.xml
@@ -1,5 +1,5 @@
 <chapter id="administration">
- <!-- $Id: administration.xml,v 1.33 2006-05-02 12:55:18 mike Exp $ -->
+ <!-- $Id: administration.xml,v 1.34 2006-06-12 09:39:18 marc Exp $ -->
  <title>Administrating Zebra</title>
  <!-- ### It's a bit daft that this chapter (which describes half of
           the configuration-file formats) is separated from
@@ -1033,10 +1033,9 @@
     <screen> 
     rank: rank-1        # default TDF-IDF like
     rank: rank-static   # dummy do-nothing
-    rank: zvrank        # configurable, experimental TDF-IDF like
     </screen>
-    Notice that the <literal>rank-1</literal> and
-    <literal>zvrank</literal> do not use the static rank 
+    Notice that the <literal>rank-1</literal> algorithm
+    does not use the static rank 
     information in the list keys, and will produce the same ordering
     with or without static ranking enabled.
    </para>
diff --git a/doc/zvrank.txt b/doc/zvrank.txt
deleted file mode 100644
index db28ac8..0000000
--- a/doc/zvrank.txt
+++ /dev/null
@@ -1,207 +0,0 @@
-Zvrank: an experimental ranking algorithm. See doc/zvrank.txt and
-source in index/zvrank.c. Enable this by using rank: zvrank in zebra.cfg.
-Contributed by Johannes Leveling <Johannes.Leveling at
-fernuni-hagen.de>
-
-
-This is an experimental addon (or patch) for the Zebra server
-to faciliate ranked searches with the Vector Space Model.
-To install the addon, copy the file 'rank1.c' in the index
-directory of the Zebra distribution to 'rank1.c.orig' and 
-replace 'rank1.c' with 'zrank1.c'. Then recompile Zebra.
-(make sure you link with the math library, so add the linker option
-'-lm'  if necessary).
-
-
-Introduction:
-=============
-In the vector space model, queries and documents are
-represented as vectors of term weights. Positive weights 
-characterise terms assigned to a document while a zero weight 
-is used for terms that do not occur in the document.
-The most popular method to obtain term weights is the tf-idf 
-weighting schema, where the weight of a term is calculated as
-the product of a term factor (tf) and an inverse document factor
-(idf). Combining the tf and idf factors (usually the product) 
-and normalizing them yields a tf-idf vector (or term weight vector) 
-modelling a document (or query).
-The similarity score between a query and a document (or the
-similarity between two documents) depends on the term weight vectors and is 
-then computed by a similarity function combining these two 
-weight vectors (most often the cosine between the vectors is computed).
-
-Weighting functions:
-====================
-1) term frequency functions:
-   locc denotes the in document frequency of a term (local frequency)
-
-   none ('n'):      tf = locc
-   binary ('b'):    tf = 1
-   max_norm ('m'):  tf = locc/max_locc
-   aug_norm ('a'):  tf = K + (1 - K) * (locc/max_locc)  ; K = 0.5
-   square ('s'):    tf = locc * locc
-   log ('l'):       tf = log(locc) + 1
-
-2) inverse document functions:
-   gocc is the database frequency of a term (global frequncy)
-   num_docs is the number of documents in the database
-
-   none ('n'):      idf = 1
-   tfidf ('t'):     idf = log (num_docs / gocc)
-   prob ('p'):      idf = log ((num_docs - gocc) / gocc)
-   freq ('f'):      idf = 1 / n
-   squared ('s'):   idf = log (num_docs / gocc) ^ 2
-
-3) weight normalisation functions:
-   wt = tf * idf
-
-   none ('n'):      nwt = wt
-   sum ('s'):       nwt = wt / sum ( wt_i )
-   cosine ('c'):    nwt = wt / sqrt ( sum ( wt_i ^2 ))    
-   fourth ('f'):    nwt = wt / sum ( wt_i ^ 4 )
-   max ('m'):       nwt = wt / max ( wt_i )
-
-
-For example, the string 'atc' indicates that the 
-augmented normalized term frequency ('a'), the 
-usual tfidf weight ('t') and cosine normalisation ('c') is to be
-used for term weight caomputation.
-
-*) similarity function:
-   - cosine ('c')
-   others are (TODO, not yet implemented): 
-   - pivoted unqiue normalisation ('p')
-   - jaccard ('j')
-   - dice ('d')
-   - minkwoski ('m')
-
-(Note: at the moment, there are 6 * 5 * 5 * 6 * 5 * 5 (* 1)
-ranking schemes selectable, but not all of them work).
-
-
-Example query (for yaz-client):
-===============================
-  find @attr 1=4 @attr 2=102 @attr 4=105 "where do i find literature on medical databases"
-Relation attribute 102 indicates that the results should be ranked by relevance
-and the query should be treated as free text (or wordlist).
-
-
-
-Pitfalls and problems:
-======================
-- The name of the ranking schema should be read from the Zebra 
-  configuration file.
-- Some weighting schemas require values to be calculated
-  that are assigned constant values in this addon.
-  For example, the db_f_max is the maximum frequency of a term 
-  in the database.
-- Ranking (or weight computation) is done online, e. g. immediately before
-  records are retrieved. A faster way to get term weights would be to store 
-  them within inverted files. Adding this feature to Zebra would require major 
-  changes for the indexing process (as far as I can tell).
-- Stopwords are frequent words considered not useful for indexing
-  documents (for example, "and", "the", "above" are common stopwords).
-  Often these words do not carry semantic information. A stopword
-  list might considerably reduce the size of the index and will probably
-  enhance precision for natural language queries. In Zebra, stopword removal
-  is possible with input filters.
-- Stemming is often used to map various morphologic forms of a
-  concept to a single representation (for example, "countries" and
-  "country" should both be stemmed to "country"). Using stemming for indexing
-  is used to increase recall. In Zebra, stemming should be part of input 
-  filtering. 
-
-
-Literature:
-===========
-* Sebastian Hammer and Adam Dickmeiss and Heikki Levanto and Mike Taylor,
-  Zebra - user's guide and reference,
-  IndexData, 1995-2003.
-
-* Gerard Salton and Chris Buckley,
-  "Term Weighting Approaches in Automatic Text Retrieval",
-  Dept. of Computer Science, Cornell University,
-  TR 87-881, November 1987.
-  Also appeared in: 
-  Information Processing and Management, vol. 24, no. 5, pp. 513--523, 1988.
-
-* Justin Zobel and Alistair Moffat,
-  Exploring the Similarity Space,
-  SIGIR Forum 32(1), p. 18-34, 1998.
-  http://citeseer.nj.nec.com/zobel98exploring.html
-
-* SMART related documents:
-  http://www.dcs.gla.ac.uk/ftp/pub/Bruin/HTML/SMART.HTM
-
-
-
-Nomenclature / glossary:
-========================
-- Database and collection are used as synonyms
-- A Document is the indexed part of a record that is referred to in a query
-  (for a title search, the title entry)
-
-* Ranking schema 
-  A ranking schema is identified by a seven character string
-  (note: this may change in the future).
-  The first three characters indicate the function to be used
-  for the documents term frequency factor, the documents
-  inverse document frequency factor and the function to combine
-  these factors to assign a term weight. 
-  The middle character is the delimiter '-'.
-  The last three characters indicate the functions for query term weighting.
-  Note that different functions may be used for query and document vectors. 
-
-  The default similarity function calculates the cosine 
-  between a document term vector and the query term vector.
-
-* Term: 
-  an atomic concept used for indexing (a string), 
-  for example a word, a phrase or a number
-* Document: 
-  In Zebra, any part of a record that has index terms assigned to
-  it. As data can (sometimes) be structured, document also refers to the 
-  smallest substructure with index terms (for example, a newspaper
-  article may be structured into its title, abstract and its body of
-  text components, which can be considered as different documents). 
-* Term weighting function:
-  the function used to combine and normalize tf and idf 
-* Term frequency factor (tf) / Local weight: 
-  It indicates how important a term is to a particular document
-  and depends on how many times a term occurs in a document.
-* Inverse document factor (idf) / Global weight: 
-  The global weight indicates how important a term is to the entire 
-  database based on the number of documents in which the term occurs.
-  The inverse document frequency is based on the observation that a less 
-  frequently occurring term has better properties discriminating 
-  documents than a term that in more documents.
-* Normalisation:   
-  the normalisation function tries to compensate for ranking discrepancies
-  (for example different document lengths).
-* Score:
-  The score of a document indicates its similarity to the query 
-  (0 <= score <=1000)
-* Rank:
-  The rank of a document is the position in the ranked result set.
-  (first document: rank 1, etc.)
-
-TODO:
-=====
-- replace 'fprintf' with 'yaz_log'
-- produce small test database and test cases
-- extend naming schema to eight chars (include similarity functions)
-- warn if schema is not fully available (e.g. if 'num_docs' or 'tf_max' 
-  are used)
-- optimize implementation (!)
-- Some structure elements are declared as integers ('int'). 
-  For larger databases, they might have to be declared as 'unsigned long int'
-- 'd_f_max_str' and 'f_max_str' are not really needed (in DS, RS)
-- 'db_num_docs' is the number of documents in the database.
-  (probably the number of sysnos) 
-  This is computed for the DBs Explain record as 'recordCount'
-  and should be avaialable as reg-> ... -> recordCount
-- 'db_terms' is the number of distinct terms used in the database.
-  (probably the number of keys)
-- maybe maximum frequencies can be computed on-the-fly for result sets
-  (in contrast to the whole set of records)
-
diff --git a/index/Makefile.am b/index/Makefile.am
index 4262ae5..d502baf 100644
--- a/index/Makefile.am
+++ b/index/Makefile.am
@@ -1,4 +1,4 @@
-## $Id: Makefile.am,v 1.40 2006-05-30 13:21:14 adam Exp $
+## $Id: Makefile.am,v 1.41 2006-06-12 09:39:18 marc Exp $
 
 noinst_PROGRAMS = apitest kdump
 
@@ -17,8 +17,8 @@ libidzebra_api_la_SOURCES = \
   recindex.c  recindex.h recindxp.h reckeys.c reckeys.h recstat.c retrieve.c \
   sortidx.c symtab.c \
   update_path.c update_file.c trunc.c \
-  zebraapi.c zinfo.c zinfo.h zserver.h zsets.c zrpn.c \
-  zvrank.c
+  zebraapi.c zinfo.c zinfo.h zserver.h zsets.c zrpn.c
+
 
 bin_PROGRAMS = zebraidx zebrasrv zebrash
 
diff --git a/index/zebraapi.c b/index/zebraapi.c
index 4ef13f8..b293fc2 100644
--- a/index/zebraapi.c
+++ b/index/zebraapi.c
@@ -1,4 +1,4 @@
-/* $Id: zebraapi.c,v 1.220 2006-06-07 10:14:41 adam Exp $
+/* $Id: zebraapi.c,v 1.221 2006-06-12 09:39:18 marc Exp $
    Copyright (C) 1995-2006
    Index Data ApS
 
@@ -383,7 +383,6 @@ struct zebra_register *zebra_register_open(ZebraService zs, const char *name,
     
     /* installing rank classes */
     zebraRankInstall (reg, rank_1_class);
-    zebraRankInstall (reg, rank_zv_class);
     zebraRankInstall (reg, rank_similarity_class);
     zebraRankInstall (reg, rank_static_class);
 
diff --git a/index/zvrank.c b/index/zvrank.c
deleted file mode 100644
index c2fc218..0000000
--- a/index/zvrank.c
+++ /dev/null
@@ -1,852 +0,0 @@
-/* $Id: zvrank.c,v 1.21 2006-05-10 08:13:26 adam Exp $
-   Copyright (C) 1995-2005
-   Index Data ApS
-
-   This file is part of the Zebra server.
-
-   Zebra is free software; you can redistribute it and/or modify it under
-   the terms of the GNU General Public License as published by the Free
-   Software Foundation; either version 2, or (at your option) any later
-   version.
-
-   Zebra is distributed in the hope that it will be useful, but WITHOUT ANY
-   WARRANTY; without even the implied warranty of MERCHANTABILITY or
-   FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
-   for more details.
-
-   You should have received a copy of the GNU General Public License
-   along with Zebra; see the file LICENSE.zebra.  If not, write to the
-   Free Software Foundation, 59 Temple Place - Suite 330, Boston, MA
-   02111-1307, USA.
-*/
-
-/*
-Zvrank: an experimental ranking algorithm. See doc/zvrank.txt and
-source in index/zvrank.c. Enable this by using rank: zvrank in zebra.cfg.
-Contributed by Johannes Leveling <Johannes.Leveling at
-fernuni-hagen.de>
-*/
-
-/* Zebra Vector Space Model RANKing 
-**
-** six (seven) letter identifier for weighting scheme
-** best document weighting:
-**  tfc nfc (tpc npc) [original naming]
-**  ntc atc  npc apc  [SMART naming, used here]
-** best query weighting:
-**  nfx tfx bfx (npx tpx bpx) [original naming]
-**  atn ntn btn  apn npn bpn  [SMART naming]
-** -> should set zvrank.weighting-scheme to one of
-** "ntc-atn", "atc-atn", etc.
-*/
-
-
-#include <math.h>  /* for log */
-
-#include <stdio.h>
-#include <assert.h>
-#ifdef WIN32
-#include <io.h>
-#else
-#include <unistd.h>
-#endif
-
-#include "index.h"
-#include "rank.h"
-
-static int log_level = 0;
-static int log_initialized = 0;
-
-static double blog(double x) { 
-    /* log_2, log_e or log_10 is used, best to change it here if necessary */
-    if (x <= 0)
-        return 0.0;
-    return log(x); /* / log(base) */
-}
-
-/* structures */
-
-struct rank_class_info {
-    char rscheme[8];    /* name of weighting scheme */
-};
-
-
-struct rs_info {      /* for result set */
-    int db_docs;        /* number of documents in database (collection) */
-    int db_terms;       /* number of distinct terms in database (debugging?) */
-    int db_f_max;       /* maximum of f_t in database (debugging?) */
-    char *db_f_max_str; /* string (most frequent term) - for debugging */
-    /**/
-    char rscheme[8];    /* name of weighting scheme */
-    /**/
-    int veclen;
-    NMEM nmem;
-    void (*d_tf_fct)(void *, void *);   /* doc term frequency function */
-    void (*d_idf_fct)(void *, void *);  /* doc idf function */
-    void (*d_norm_fct)(void *, void *); /* doc normalization function */
-    /**/
-    void (*q_tf_fct)(void *, void *);   /* query term frequency function */
-    void (*q_idf_fct)(void *, void *);  /* query idf function */
-    void (*q_norm_fct)(void *, void *); /* query normalization function */
-    
-    double (*sim_fct)(void *, void *);  /* similarity function (scoring function) */
-    struct ds_info *qdoc;
-    struct ds_info *rdoc;
-};
-typedef struct rs_info *RS;
-
-static void prn_rs(RS rs) { /* for debugging */
-    yaz_log(log_level, "* RS:");
-    yaz_log(log_level, " db_docs:   %d", rs->db_docs);
-    yaz_log(log_level, " db_terms:  %d", rs->db_terms);
-    yaz_log(log_level, " f_max:     %d", rs->db_f_max);
-    yaz_log(log_level, " f_max_str: %s", rs->db_f_max_str);
-    yaz_log(log_level, " veclen:    %d", rs->veclen);
-    /* rscheme implies functions */
-    yaz_log(log_level, " rscheme:   %s", rs->rscheme);
-    return;
-}
-
-struct ds_info {       /* document info */
-    char *docid;         /* unique doc identifier */
-    int  docno;          /* doc number */
-    int doclen;          /* document length */
-    int d_f_max;         /* maximum number of any term in doc (needed) */
-    char *d_f_max_str;   /* most frequent term in d - for debugging */
-    int veclen;          /* vector length */
-    struct ts_info *terms;
-    double docsim;       /* similarity in [0, ..., 1] (= score/1000) */
-};
-typedef struct ds_info* DS;
-
-#if 0
-static void prn_ds(DS ds) { /* for debugging */
-    yaz_log(log_level, " * DS:");
-    yaz_log(log_level, " docid:      %s", ds->docid);
-    yaz_log(log_level, " docno:      %d", ds->docno);
-    yaz_log(log_level, " doclen:     %d", ds->doclen);
-    yaz_log(log_level, " d_f_max:    %d", ds->d_f_max);
-    yaz_log(log_level, " d_f_max_str:%s", ds->d_f_max_str);
-    yaz_log(log_level, " veclen:     %d", ds->veclen);
-    return;
-}
-#endif
-
-struct ts_info {       /* term info */
-    char *name;
-    int *id;
-    /**/
-    zint gocc;
-    int locc;
-    double tf;
-    double idf;
-    double wt;
-};
-typedef struct ts_info *TS;
-
-#if 0
-static void prn_ts(TS ts) { /* for debugging */
-    yaz_log(log_level, " * TERM:%s gocc:%d locc:%d  tf:%f idf:%f wt:%f",
-            ts->name, ts->gocc, ts->locc, ts->tf, ts->idf, ts->wt);
-    return;
-}
-#endif
-
-/* end structures */
-
-/* *** */
-
-/* 
-** weighting functions 
-** check: RS is not needed anymore
-*/
-
-/* calculate and store new term frequency vector */
-static void tf_none(void *rsi, void *dsi) {
-    DS ds=(DS)dsi;
-    int i, veclen, freq;
-    /* no conversion. 1 <= tf */
-    veclen=ds->veclen;
-    for (i=0; i < veclen; i++) {
-        freq=ds->terms[i].locc;
-        ds->terms[i].tf=freq;
-    }
-    return;
-}
-
-static void tf_binary(void *rsi, void *dsi) {
-    DS ds=(DS)dsi;
-    int i, veclen, freq;
-    /* tf in {0, 1} */
-    veclen=ds->veclen;
-    for (i=0; i < veclen; i++) {
-        freq=ds->terms[i].locc;
-        if (freq > 0)
-            ds->terms[i].tf=1.0;
-        else
-            ds->terms[i].tf=0.0;
-    }
-    return;
-}
-
-static void tf_max_norm(void *rsi, void *dsi) {
-    DS ds=(DS)dsi;
-    double tf_max;
-    int i, veclen, freq;
-    /* divide each term by max, so 0 <= tf <= 1 */
-    tf_max=ds->d_f_max; /* largest frequency of t in document */
-    veclen=ds->veclen;
-    for (i=0; i < veclen; i++) {
-        freq=ds->terms[i].locc;
-        if ((freq > 0) &&
-            (tf_max > 0.0)) 
-            ds->terms[i].tf=freq/tf_max;
-        else
-            ds->terms[i].tf=0.0;
-    }
-    return;
-}
-
-static void tf_aug_norm(void *rsi, void *dsi) {
-    DS ds=(DS)dsi;
-    double K; 
-    double tf_max;
-    int i, veclen, freq;
-    /* augmented normalized tf. 0.5 <= tf <= 1  for K = 0.5 */
-    tf_max=ds->d_f_max; /* largest frequency of t in document */
-    veclen=ds->veclen;
-    K=0.5; /* zvrank.const-K */
-    for (i=0; i < veclen; i++) {
-        freq=ds->terms[i].locc;
-        if ((freq > 0) &&
-            (tf_max > 0.0)) 
-            ds->terms[i].tf=K+(1.0-K)*(freq/tf_max);
-        else
-            ds->terms[i].tf=0.0;
-    }
-    return;
-}
-
-static void tf_square(void *rsi, void *dsi) {
-    DS ds=(DS)dsi;
-    int i, veclen, freq;
-    /* tf ^ 2 */
-    veclen=ds->veclen;
-    for (i=0; i < veclen; i++) {
-        freq=ds->terms[i].locc;
-        if (freq > 0) 
-            ds->terms[i].tf=freq*freq;
-        else
-            ds->terms[i].tf=0.0;
-    }
-    return;
-}
-
-static void tf_log(void *rsi, void *dsi) {
-    DS ds=(DS)dsi;
-    int i, veclen, freq;
-    /* logarithmic tf */    
-    veclen=ds->veclen;
-    for (i=0; i < veclen; i++) {
-        freq=ds->terms[i].locc;
-        if (freq > 0) 
-            ds->terms[i].tf=1.0+blog(freq);
-        else
-            ds->terms[i].tf=0.0;
-    }
-    return;
-}
-
-/* calculate and store inverse document frequency vector */
-static void idf_none(void *rsi, void *dsi) {
-    DS ds=(DS)dsi;
-    int i, veclen;
-    /* no conversion */
-    veclen=ds->veclen;
-    for (i=0; i < veclen; i++) {
-        ds->terms[i].idf=1.0;
-    }
-    return;
-}
-
-static void idf_tfidf(void *rsi, void *dsi) {
-    RS rs=(RS)rsi;
-    DS ds=(DS)dsi;
-    zint num_docs, gocc;
-    int i, veclen;
-    double idf;
-    /* normal tfidf weight */
-    veclen=ds->veclen;
-    num_docs=rs->db_docs;
-    for (i=0; i < veclen; i++) {
-        gocc=ds->terms[i].gocc;
-        if (gocc==0) 
-            idf=0.0; 
-        else
-            idf=blog((double) (num_docs/gocc));
-        ds->terms[i].idf=idf;
-    }
-    return;
-}
-
-static void idf_prob(void *rsi, void *dsi) {
-    RS rs=(RS)rsi;
-    DS ds=(DS)dsi;
-    zint num_docs, gocc;
-    int i, veclen;
-    double idf;
-    /* probabilistic formulation */
-    veclen=ds->veclen;
-    num_docs=rs->db_docs;
-    for (i=0; i < veclen; i++) {
-        gocc=ds->terms[i].gocc;
-        if (gocc==0)
-            idf=0.0; 
-        else
-            idf=blog((double) ((num_docs-gocc)/gocc));
-        ds->terms[i].idf=idf;
-    }
-    return;
-}
-
-static void idf_freq(void *rsi, void *dsi) {
-    RS rs=(RS)rsi;
-    DS ds=(DS)dsi;
-    int num_docs;
-    int i, veclen;
-    double idf;
-    /* frequency formulation */
-    veclen=ds->veclen;
-    num_docs=rs->db_docs;
-    if (num_docs==0)
-        idf=0.0;
-    else
-        idf=1.0/num_docs;
-    for (i=0; i < veclen; i++) {
-        ds->terms[i].idf=idf;
-    }
-    return;
-}
-
-static void idf_squared(void *rsi, void *dsi) {
-    RS rs=(RS)rsi;
-    DS ds=(DS)dsi;
-    zint num_docs, gocc;
-    int i, veclen;
-    double idf;
-    /* idf ^ 2 */
-    veclen=ds->veclen;
-    num_docs=rs->db_docs;
-    yaz_log(log_level, "idf_squared: db_docs required");
-    for (i=0; i < veclen; i++) {
-        gocc=ds->terms[i].gocc;
-        if (gocc==0)
-            idf=0.0;
-        else 
-            idf=blog(CAST_ZINT_TO_DOUBLE(num_docs/gocc));
-        idf=idf*idf;
-        ds->terms[i].idf=idf;
-    }
-    return;
-}
-
-/* calculate and store normalized weight (tf-idf) vector */
-static void norm_none(void *rsi, void *dsi) {
-    DS ds=(DS)dsi;
-    int i, veclen;
-    /* no normalization */
-    veclen=ds->veclen;
-    for (i=0; i < veclen; i++) {
-        ds->terms[i].wt=ds->terms[i].tf*ds->terms[i].idf;
-    }
-    return;
-}
-
-static void norm_sum(void *rsi, void *dsi) {
-    DS ds=(DS)dsi;
-    int i, veclen;
-    double tfs=0.0;
-    /**/
-    veclen=ds->veclen;
-    for (i=0; i < veclen; i++) {
-        ds->terms[i].wt=ds->terms[i].tf*ds->terms[i].idf;
-        tfs+=ds->terms[i].wt;
-    } 
-    if (tfs > 0.0)
-        for (i=0; i < veclen; i++) {
-            ds->terms[i].wt=ds->terms[i].wt/tfs;
-        }
-    /* else: tfs==0 && ds->terms[i].wt==0 */
-    return;
-}
-
-static void norm_cosine(void *rsi, void *dsi) {
-    DS ds=(DS)dsi;
-    int i, veclen;
-    double tfs=0.0;
-    /**/
-    veclen=ds->veclen;
-    for (i=0; i < veclen; i++) {
-        ds->terms[i].wt=ds->terms[i].tf*ds->terms[i].idf;
-        tfs+=(ds->terms[i].wt*ds->terms[i].wt);
-    } 
-    tfs=sqrt(tfs); 
-    if (tfs > 0.0)
-        for (i=0; i < veclen; i++) {
-            ds->terms[i].wt=ds->terms[i].wt/tfs;
-        }
-    /* else: tfs==0 && ds->terms[i].wt==0 */
-    return;
-}
-
-static void norm_fourth(void *rsi, void *dsi) {
-    DS ds=(DS)dsi;
-    int i, veclen;
-    double tfs=0.0, fr;
-    /**/
-    veclen=ds->veclen;
-    for (i=0; i < veclen; i++) {
-        ds->terms[i].wt=ds->terms[i].tf*ds->terms[i].idf;
-        fr=(ds->terms[i].wt*ds->terms[i].wt);
-        fr=fr*fr; /* ^ 4 */
-        tfs+=fr; 
-    }
-    if (tfs > 0.0)
-        for (i=0; i < veclen; i++) {
-            ds->terms[i].wt=ds->terms[i].wt/tfs;
-        }
-    /* else: tfs==0 && ds->terms[i].wt==0 */
-    return;
-}
-
-static void norm_max(void *rsi, void *dsi) {
-    DS ds=(DS)dsi;
-    int i, veclen;
-    double tfm=0.0;
-    /**/
-    veclen=ds->veclen;
-    for (i=0; i < veclen; i++) {
-        ds->terms[i].wt=ds->terms[i].tf*ds->terms[i].idf;
-        if (ds->terms[i].wt > tfm)
-            tfm=ds->terms[i].wt;
-    }
-    if (tfm > 0.0)
-        for (i=0; i < veclen; i++) {
-            ds->terms[i].wt=ds->terms[i].wt/tfm;
-        }
-    /* else: tfs==0 && ds->terms[i].wt==0 */
-    return;
-}
-
-/* FIXME add norm_pivot, ... */
-
-static double sim_cosine(void *dsi1, void *dsi2) {
-    DS ds1=(DS)dsi1;
-    DS ds2=(DS)dsi2;
-    int i, veclen;
-    double smul=0.0, sdiv=0.0, sqr11=0.0, sqr22=0.0;
-    double v1, v2;
-    /**/
-    veclen=ds1->veclen; /* and ds2->veclen */
-    for (i=0; i < veclen; i++) {
-        v1=ds1->terms[i].wt;
-        v2=ds2->terms[i].wt;
-        smul +=(v1*v2);
-        sqr11+=(v1*v1);
-        sqr22+=(v2*v2);
-    }
-    sdiv=sqrt(sqr11*sqr22);
-    if (sdiv==0.0)
-        return 0.0;
-    return (smul/sdiv);
-}
-
-/* FIXME: add norm_jaccard, norm_dice, ... */
-
-/* end weighting functions */
-
-/* *** */
-
-static void zv_init_scheme(RS rs, const char *sname) {
-    int slen;
-    char c0, c1, c2, c3, c4, c5, c6;
-    const char *def_rscheme="ntc-atn"; /* a good default */
-    /**/
-    yaz_log(log_level, "zv_init_scheme");
-    slen=strlen(sname);
-    if (slen < 7) 
-        yaz_log(log_level, "zvrank: invalid weighting-scheme \"%s\"", sname);
-    if (slen > 0) c0=sname[0]; else c0=def_rscheme[0];
-    if (slen > 1) c1=sname[1]; else c1=def_rscheme[1];
-    if (slen > 2) c2=sname[2]; else c2=def_rscheme[2];
-    c3='-';
-    if (slen > 4) c4=sname[4]; else c4=def_rscheme[4];
-    if (slen > 5) c5=sname[5]; else c5=def_rscheme[5];
-    if (slen > 6) c6=sname[6]; else c6=def_rscheme[6];
-    
-    /* assign doc functions */
-    switch (c0) 
-    {
-        case 'b':
-            rs->d_tf_fct=tf_binary;
-            rs->rscheme[0]='b';
-            break;
-        case 'm':
-            rs->d_tf_fct=tf_max_norm;
-            rs->rscheme[0]='m';
-            yaz_log(log_level, "tf_max_norm: d_f_max required");
-            break;
-        case 'a':
-            rs->d_tf_fct=tf_aug_norm;
-            rs->rscheme[0]='a';
-            yaz_log(log_level, "tf_aug_norm: d_f_max required");
-            break;
-        case 's':
-            rs->d_tf_fct=tf_square;
-            rs->rscheme[0]='s';
-            break;
-        case 'l':
-            rs->d_tf_fct=tf_log;
-            rs->rscheme[0]='l';
-            break;
-        default: /* 'n' */
-            rs->d_tf_fct=tf_none;
-            rs->rscheme[0]='n';
-    }
-    switch (c1) 
-    {
-        case 't':
-            rs->d_idf_fct=idf_tfidf;
-            rs->rscheme[1]='t';
-            yaz_log(log_level, "idf_tfidf: db_docs required");
-            break;
-        case 'p':
-            rs->d_idf_fct=idf_prob;
-            rs->rscheme[1]='p';
-            yaz_log(log_level, "idf_prob: db_docs required");
-            break;
-        case 'f':
-            rs->d_idf_fct=idf_freq;
-            rs->rscheme[1]='f';
-            yaz_log(log_level, "idf_freq: db_docs required");
-            break;
-        case 's':
-            rs->d_idf_fct=idf_squared;
-            rs->rscheme[1]='s';
-            yaz_log(log_level, "idf_squared: db_docs required");
-            break;
-        default: /* 'n' */
-            rs->d_idf_fct=idf_none;
-            rs->rscheme[1]='n';
-    }
-    switch (c2) 
-    {
-        case 's':
-            rs->d_norm_fct=norm_sum;
-            rs->rscheme[2]='s';
-            break;
-        case 'c':
-            rs->d_norm_fct=norm_cosine;
-            rs->rscheme[2]='c';
-            break;
-        case 'f':
-            rs->d_norm_fct=norm_fourth;
-            rs->rscheme[2]='t';
-            break;
-        case 'm':
-            rs->d_norm_fct=norm_max;
-            rs->rscheme[2]='m';
-            break;
-        default: /* 'n' */
-            rs->d_norm_fct=norm_none;
-            rs->rscheme[2]='n';
-    }
-    rs->rscheme[3]='-';
-    /* assign query functions */
-    switch (c4) 
-    {
-        case 'b':
-            rs->q_tf_fct=tf_binary;
-            rs->rscheme[4]='b';
-            break;
-        case 'm':
-            rs->q_tf_fct=tf_max_norm;
-            yaz_log(log_level, "tf_max_norm: d_f_max required");
-            rs->rscheme[4]='m';
-            break;
-        case 'a':
-            rs->q_tf_fct=tf_aug_norm;
-            rs->rscheme[4]='a';
-            yaz_log(log_level, "tf_aug_norm: d_f_max required");
-            break;
-        case 's':
-            rs->q_tf_fct=tf_square;
-            rs->rscheme[4]='s';
-            break;
-        case 'l':
-            rs->q_tf_fct=tf_log;
-            rs->rscheme[4]='l';
-            break;
-        default: /* 'n' */
-            rs->q_tf_fct=tf_none;
-            rs->rscheme[4]='n';
-    }
-    switch (c5) 
-    {
-        case 't':
-            rs->q_idf_fct=idf_tfidf;
-            rs->rscheme[5]='t';
-            yaz_log(log_level, "idf_tfidf: db_docs required");
-            break;
-        case 'p':
-            rs->q_idf_fct=idf_prob;
-            rs->rscheme[5]='p';
-            yaz_log(log_level, "idf_prob: db_docs required");
-            break;
-        case 'f':
-            rs->q_idf_fct=idf_freq;
-            rs->rscheme[5]='f';
-            yaz_log(log_level, "idf_freq: db_docs required");
-            break;
-        case 's':
-            rs->q_idf_fct=idf_squared;
-            rs->rscheme[5]='s';
-            yaz_log(log_level, "idf_squared: db_docs required");
-            break;
-        default: /* 'n' */
-            rs->q_idf_fct=idf_none;
-            rs->rscheme[5]='n';
-    }
-    switch (c6) 
-    {
-        case 's':
-            rs->q_norm_fct=norm_sum;
-            rs->rscheme[6]='s';
-            break;
-        case 'c':
-            rs->q_norm_fct=norm_cosine;
-            rs->rscheme[6]='c';
-            break;
-        case 'f':
-            rs->q_norm_fct=norm_fourth;
-            rs->rscheme[6]='f';
-            break;
-        case 'm':
-            rs->q_norm_fct=norm_max;
-            rs->rscheme[6]='m';
-            break;
-        default: /* 'n' */
-            rs->q_norm_fct=norm_none;
-            rs->rscheme[6]='n';
-    }
-    rs->rscheme[7]='\0';
-    rs->sim_fct=sim_cosine;
-    yaz_log(log_level, "zv_scheme %s", rs->rscheme);
-}
-
-static void zv_init(RS rs, const char *rscheme) {
-    yaz_log(log_level, "zv_init");
-    /**/
-    rs->db_docs=100000;   /* assign correct value here */
-    rs->db_terms=500000;  /* assign correct value here (for debugging) */
-    rs->db_f_max=50;      /* assign correct value here */
-    rs->db_f_max_str="a"; /* assign correct value here (for debugging) */
-    /* FIXME - get those values from somewhere */
-    zv_init_scheme(rs, rscheme);
-    return;
-}
-
-/******/
-
-/*
- * zv_create: Creates/Initialises this rank handler. This routine is 
- *  called exactly once. The routine returns the class_handle.
- */
-static void *zv_create (ZebraHandle zh) {
-    int i;
-    Res res = zh->res;
-    const char *wscheme;
-    struct rank_class_info *ci = (struct rank_class_info *)
-        xmalloc (sizeof(*ci));
-    if (!log_initialized)
-    {
-        log_level = yaz_log_module_level("zvrank");
-        log_initialized = 1;
-    }
-
-    yaz_log(log_level, "zv_create");
-    wscheme=  res_get_def(res, "zvrank.weighting-scheme", "");
-    for (i = 0; wscheme[i] && i < 8; i++) 
-        ci->rscheme[i]=wscheme[i];
-    ci->rscheme[i] = '\0';
-    return ci;
-}
-
-/*
- * zv_destroy: Destroys this rank handler. This routine is called
- *  when the handler is no longer needed - i.e. when the server
- *  dies. The class_handle was previously returned by create.
- */
-static void zv_destroy (struct zebra_register *reg, void *class_handle) {
-    struct rank_class_info *ci = (struct rank_class_info *) class_handle;
-    yaz_log(log_level, "zv_destroy");
-    xfree (ci);
-}
-
-
-/*
- * zv_begin: Prepares beginning of "real" ranking. Called once for
- *  each result set. The returned handle is a "set handle" and
- *  will be used in each of the handlers below.
- */
-static void *zv_begin(struct zebra_register *reg, void *class_handle, 
-                      RSET rset, NMEM nmem, TERMID *terms, int numterms)
-{
-    struct rs_info *rs=(struct rs_info *)nmem_malloc(nmem,sizeof(*rs));
-    struct rank_class_info *ci=(struct rank_class_info *)class_handle;
-    int i;
-    int veclen;
-    int *ip;
-    zint gocc;
-    /**/
-    yaz_log(log_level, "zv_begin");
-    veclen= numterms;
-    zv_init(rs, ci->rscheme);
-    rs->nmem=nmem;
-    rs->veclen=veclen;
-    prn_rs(rs);
-  
-    rs->qdoc=(struct ds_info *)nmem_malloc(nmem,sizeof(*rs->qdoc));
-    rs->qdoc->terms=(struct ts_info *)nmem_malloc(nmem,
-                                sizeof(*rs->qdoc->terms)*rs->veclen);
-    rs->qdoc->veclen=veclen;
-    rs->qdoc->d_f_max=1; /* no duplicates */ 
-    rs->qdoc->d_f_max_str=""; 
-
-    rs->rdoc=(struct ds_info *)nmem_malloc(nmem,sizeof(*rs->rdoc));
-    rs->rdoc->terms=(struct ts_info *)nmem_malloc(nmem,
-                         sizeof(*rs->rdoc->terms)*rs->veclen);
-    rs->rdoc->veclen=veclen;
-    rs->rdoc->d_f_max=10; /* just a guess */
-    rs->rdoc->d_f_max_str=""; 
-    /* yaz_log(log_level, "zv_begin_init"); */
-    for (i = 0; i < rs->veclen; i++)
-    {
-        gocc= rset_count(terms[i]->rset);
-        terms[i]->rankpriv=ip=nmem_malloc(nmem, sizeof(int));
-        *ip=i; /* save the index for add() */
-        /* yaz_log(log_level, "zv_begin_init i=%d gocc=%d", i, gocc); */
-        rs->qdoc->terms[i].gocc=gocc;
-        rs->qdoc->terms[i].locc=1;  /* assume query has no duplicate terms */
-        rs->rdoc->terms[i].gocc=gocc;
-        rs->rdoc->terms[i].locc=0;
-    }
-    (*rs->q_tf_fct)(rs, rs->qdoc); /* we do this once only */
-    (*rs->q_idf_fct)(rs, rs->qdoc);
-    (*rs->q_norm_fct)(rs, rs->qdoc);
-    return rs;
-}
-
-/*
- * zv_end: Terminates ranking process. Called after a result set
- *  has been ranked.
- */
-static void zv_end (struct zebra_register *reg, void *rsi)
-{
-    yaz_log(log_level, "zv_end");
-    /* they all are nmem'd */
-    return;
-}
-
-/*
- * zv_add: Called for each word occurence in a result set. This routine
- *  should be as fast as possible. This routine should "incrementally"
- *  update the score.
- */
-static void zv_add (void *rsi, int seqno, TERMID term) {
-    RS rs=(RS)rsi;
-    int *ip = term->rankpriv;
-    int i=*ip;
-    if (!term) 
-    {
-        yaz_log(log_level, "zvrank zv_add seqno=%d NULL term",seqno );
-        return;
-    }
-    rs->rdoc->terms[i].locc++;
-    yaz_log(log_level, "zvrank zv_add seqno=%d '%s' term_index=%d cnt=%d", 
-             seqno, term->name, i, rs->rdoc->terms[i].locc );
-}
-
-/*
- * zv_calc: Called for each document in a result. This handler should 
- *  produce a score based on previous call(s) to the add handler. The
- *  score should be between 0 and 1000. If score cannot be obtained
- *  -1 should be returned.
- */
-static int zv_calc (void *rsi, zint sysno, zint staticrank, int *stop_flag)
-{
-    int i, veclen; 
-    int score=0;
-    double dscore=0.0;
-    RS rs=(RS)rsi;
-    /* yaz_log(log_level, "zv_calc"); */
-    /**/
-    veclen=rs->veclen;
-    if (veclen==0)
-        return -1;
-    for (i = 0; i < veclen; i++) {
-        /* qdoc weight has already been calculated */
-        (*rs->d_tf_fct)(rs, rs->rdoc);
-        (*rs->d_idf_fct)(rs, rs->rdoc);
-        (*rs->d_norm_fct)(rs, rs->rdoc);
-        dscore=rs->sim_fct(rs->qdoc, rs->rdoc);
-    }
-    score = (int) (dscore * 1000 +.5);
-    yaz_log (log_level, "zv_calc: sysno=" ZINT_FORMAT " score=%d", 
-            sysno, score);
-    if (score > 1000) /* should not happen */
-        score = 1000;
-    /* reset counts for the next record */
-    for (i = 0; i < rs->veclen; i++)
-        rs->rdoc->terms[i].locc=0;
-    return score;
-}
-
-/*
- * Pseudo-meta code with sequence of calls as they occur in a
- * server. Handlers are prefixed by --:
- *
- *     server init
- *     -- create
- *     foreach search
- *        rank result set
- *        -- begin
- *        foreach record
- *           foreach word
- *              -- add
- *           -- calc
- *        -- end
- *     -- destroy
- *     server close
- */
-
-static struct rank_control rank_control_vsm = {
-    "zvrank",
-    zv_create,
-    zv_destroy,
-    zv_begin,
-    zv_end,
-    zv_calc,
-    zv_add,
-};
- 
-struct rank_control *rank_zv_class = &rank_control_vsm;
-
-/*
- * Local variables:
- * c-basic-offset: 4
- * indent-tabs-mode: nil
- * End:
- * vim: shiftwidth=4 tabstop=8 expandtab
- */
-
-- 
1.7.10.4