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math.c

/*    Copyright (C) 1998 XIAO, Gang of Universite de Nice - Sophia Antipolis
 *
 *  This program 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 of the License, or
 *  (at your option) any later version.
 *
 *  This program 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 this program; if not, write to the Free Software
 *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

      /* Subroutines to manipulate math expressions */


      /* Points to the start of a mathematics variable (or number) */
char *find_mathvar_start(char *p)
{
    int i;
    for(i=0;!isalnum(*p) && *p!='.' && *p!=0 && i<MAX_LINELEN; p++,i++);
    return p;
}

      /* Points to the end of a mathematics variable (or number) */
char *find_mathvar_end(char *p)
{
    int i; char *pp;
    if(!isalnum(*p) && *p!='.') return p;
    if(isalpha(*p)) {
      for(i=0; *p!=0 && (isalnum(*p) || *p=='.' || *p=='\'')
          && i<MAX_LINELEN;p++,i++);
      return p;
    }
    else {
      int t=0;
      expon:
      for(i=0; (isdigit(*p) || *p=='.') && i<MAX_LINELEN;p++,i++);
      pp=p; if(t) return pp;
      while(isspace(*p)) p++;
      if(*p=='e' || *p=='E'){
          t=1; p++; while(isspace(*p)) p++;
          if(isdigit(*p)) goto expon;
          if((*p=='-' || *p=='+') && isdigit(*(p+1))) {
            p++; goto expon;
          }
      }
      return pp;
    }
}

      /* list variable (function) names in an expression.
       * buffer is modified to contain the list. */
void mathvarlist(char *p)
{
    char buf[MAX_LINELEN+1], *pb, *pe, *pp;
    char *l[10240];
    int i,j,len, nofn=0;

    pb=find_word_start(p);pe=find_word_end(pb);
    if(pe-pb==strlen("nofn") && memcmp(pb,"nofn",strlen("nofn"))==0) {
      nofn=1; pb=find_word_start(pe);
    }
    snprintf(buf,sizeof(buf),"%s",pb);
    len=strlen(buf);
    for(i=0,pb=buf;pb<buf+len;pb++) {
      if(!isalpha(*pb)) continue;
      if(pb>buf && isalnum(*(pb-1))) {
          pb=find_mathvar_end(pb); continue;
      }
      pe=find_mathvar_end(pb); pp=find_word_start(pe);
      if(nofn && *pp=='(') {
          pb=pe; continue;
      }
      *pe=0;
      if(i<10240) {
          for(j=0;j<i;j++) if(strcmp(pb,l[j])==0) goto nextp;
          l[i++]=pb;
      }
      nextp:
      pb=pe;
    }
    for(*p=0,j=0;j<i;j++) {
      strcat(p,l[j]);
      if(j<i-1) strcat(p,",");
    }
}


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