/*------------------------------------------------------------------------
 *    Graphic library
 *    Copyright (C) 1998-2001 Enpc/Jean-Philippe Chancelier
 *    jpc@cermics.enpc.fr 
 --------------------------------------------------------------------------*/
/*------------------------------------------------------------------------
 * Axis drawing for 2d plots (format selection) 
 * 
 * void  ChoixFormatE(fmt, desres, xmin, xmax, xpas) : find a format 
 * void  ChoixFormatE1(fmt, desres, xx, nx)          : find a format 
 * int   C2F(graduate)(xmi,xma,xi,xa,np1,np2,kminr,kmaxr,ar) 
 *                : change [xmi,xmax] for pretty graduation 
 *--------------------------------------------------------------------------*/

#include <math.h>
#include <string.h>
#include <stdio.h>
#include "Math.h"

/* Add those lines for FD algo on Theticks */
#define ROUND(x) (x<0?ceil((x)-0.5):floor((x)+0.5))
#define  ABS(a)  ((a) < 0.0 ? -(a) : (a))

static double spans[18] = {10,12,14,15,16,18,20,25,30,35,40,45,50,60,70,80,90,100};
static int ticks[18] = {11,7,8,4,9,10,11,6,7,8,9,10,11,7,8,9,10,11};
static double width[18] = {1,2,2,5,2,2,2,5,5,5,5,5,5,10,10,10,10,10};
/* end here */

extern double C2F(dlamch)  __PARAMS((char *CMACH, unsigned long int));

static void FormatPrec __PARAMS((char *fmt, integer *desres, double xmin, double xmax, 
				double xpas));
static void FormatPrec1 __PARAMS((char *fmt, integer *desres, double *xx, integer nx));
static int Fsepare __PARAMS((char *fmt, integer dec, integer *l, double xmin, double xmax, 
			    double xpas));
static int Fsepare1 __PARAMS((char *fmt, integer dec, integer *l, double *xx, integer nx));
static void graduate1 __PARAMS((double *xmi,double * xma,double * xi,double * xa,
			       integer * np1,integer * np2,integer * kminr,integer * kmaxr,integer * ar,int count));

static void gradua __PARAMS(( double *xmi, double *xma,integer * kminr,integer *kmaxr,integer *ar,integer *npr,integer *b));
static void decompSup __PARAMS((double x,integer * xk,integer *  xa,integer   b));
static void decompInf __PARAMS((double x,integer * xk,integer *  xa,integer   b));

static void flexpo1  __PARAMS((double *x, double *f, double *sg, double *scale));
static void newbnds  __PARAMS((double *xminv,double *xmaxv,double *xmin, double *xmax, double *scale));
static int  gradu    __PARAMS((double *xmin, double *xmax, double *grads, int *nticks, double *thewidth, int *tst0, double *scal));
static int  gradu2   __PARAMS((double *xmax, double *thewidth, double *scal));
static void grds     __PARAMS((double *xminv, double *xmaxv, double *gr, int *nticks, double *thewidth, int *tst0, double *scal));
static int  agrandir __PARAMS((double *xmin, double *xmax, double *xlow, double *xup));

/*----------------------------------------------------
 * ChoixFormatE returns a format ("%.*f" or "%.*e")
 * in fmt given xmin,xmax,pas. 
 *   fmt : character string 
 * fmt gives a format which can be used to display
 * number in range xmin:step:xmax  
 * Exemple : ChoixFormatE(format,min,max,step);
 *           fprintf(format,min+k*step);
 * The format is searched so as to give distinct values 
 * for the numeric values xmin + k*xpas in [xmin,xmax] 
 * and give enough precision. 
 *------------------------------------------------*/

void ChoixFormatE(char *fmt, double xmin, double xmax, double xpas)
{
  char c;
  integer des,len;
  /* format f minimal  */
  for ( des = 0 ; des < 5 ; des++)
    {
      if (Fsepare("%.*f",des,&len,xmin,xmax,xpas)) break;
    }
  if ( des < 5 && len <= 6)
    {
      c='f';
      strcpy(fmt,"%.*f");
    }
  else 
    {
      for ( des = 0 ; des < 5 ; des++)
	{
	  if (Fsepare("%.*e",des,&len,xmin,xmax,xpas)) break;
	}
      c='e';
      strcpy(fmt,"%.*e");
    }
  FormatPrec(fmt,&des,xmin,xmax,xpas);
  sprintf(fmt,"%%.%d%c",des,c);
}

/*
 *  checks if given format gives enough precision 
 *  if not increase it (i.e increase desres) 
 */

static void FormatPrec(char *fmt, integer *desres, double xmin, double xmax, double xpas)
{
  char buf1[100],buf2[100];
  integer i=0;
  while ( xmin+((double)i)*xpas < xmax && *desres  < 10 )
    {
      double x1,x2,yy1;
      yy1=xmin+((double) i)*xpas;
      sprintf(buf1,fmt,*desres,yy1);
      sprintf(buf2,fmt,*desres,yy1+xpas );
      sscanf(buf1,"%lf",&x1);
      sscanf(buf2,"%lf",&x2);
      if (  Abs((x2-x1 -xpas) /xpas) >= 0.1)  *desres += 1;
      if (  Abs((x1- yy1)/xpas) >= 0.01) *desres +=1;
      i++;
    }
}

/*
 *  checks if format fmt gives different values for numbers 
 *  from xmin to xmax with step xpas. It also returns in variable l
 *  the string length that will result in using the format 
 */

static int Fsepare(char *fmt, integer dec, integer *l, double xmin, double xmax, double xpas)
{
  double x=xmin;
  char buf1[100],buf2[100];
  *l = 0;
  /**  Take care of : sprintf(buf1,"%.*f",0,1.d230) which overflow in buf1 **/
  /**  we don't use %.*f format if numbers are two big **/
  if (strcmp("%.*f",fmt)==0 && (Abs(xmax)> 1.e+10 || Abs(xmin) > 1.e+10))
    return(0);
  sprintf(buf1,fmt,dec,xmin);
  while ( x < xmax ) 
    { x += xpas;
      strcpy(buf2,buf1);
      sprintf(buf1,fmt,dec,x);
      *l = (((int)strlen(buf1) >= *l) ? strlen(buf1) : *l) ;
      if ( strcmp(buf1,buf2) == 0) return(0);
    }
  return(1);
}

/*--------------------------------------------
 * same as ChoixFormatE when numbers are given through an 
 * array xx[0:nx-1];
 *------------------------------------------------*/

void ChoixFormatE1(char *fmt, double *xx, integer nx)
{
  char c;
  integer des,len;
  /* format f minimal  */
  for ( des = 0 ; des < 5 ; des++)
    {
      if (Fsepare1("%.*f",des,&len,xx,nx)) break;
    }
  if ( des < 5 && len <= 6)
    {
      c='f';
      strcpy(fmt,"%.*f");
    }
  else 
    {
      for ( des = 0 ; des < 5 ; des++)
	{
	  if (Fsepare1("%.*e",des,&len,xx,nx)) break;
	}
      c='e';
      strcpy(fmt,"%.*e");
    }
  FormatPrec1(fmt,&des,xx,nx);
  sprintf(fmt,"%%.%d%c",des,c);
}


/*----------------------------------------------------------
 *  checks if format fmt gives different values for numbers 
 *  from xmin to xmax with step xpas. It also returns in variable l
 *  the string length that will result in using the format 
 *------------------------------------------------------*/

static void FormatPrec1(char *fmt, integer *desres, double *xx, integer nx)
{
  char buf1[100],buf2[100];
  double xpas;
  integer i=0;
  while ( i < nx-1 && *desres  < 10 )
    {
      double x1,x2;
      sprintf(buf1,fmt,*desres,xx[i]);
      sprintf(buf2,fmt,*desres,xx[i+1]);
      sscanf(buf1,"%lf",&x1);
      sscanf(buf2,"%lf",&x2);
      xpas = xx[i+1]-xx[i];
      if ( xpas != 0.0)
	{
	  if (Abs((x2-x1 - xpas) /xpas) >= 0.1)  *desres += 1;
	  if (Abs((x1-xx[i])/xpas) >= 0.1) *desres +=1;
	}
      i++;
    }
}

static int Fsepare1(char *fmt, integer dec, integer *l, double *xx, integer nx)
{
  char buf1[100],buf2[100];
  integer i=0;
  *l = 0;
  /**  Take care of : sprintf(buf1,"%.*f",0,1.d230) which overflow in buf1 **/
  /**  we don't use %.*f format if numbers are two big **/
  if (strcmp("%.*f",fmt)==0 && (Abs(xx[nx-1])> 1.e+10 || Abs(xx[0]) > 1.e+10))
    return(0);
  sprintf(buf1,fmt,dec,xx[0]);
  for ( i=1 ; i < nx ; i++)
    { strcpy(buf2,buf1);
      sprintf(buf1,fmt,dec,xx[i]);
      *l = (((int)strlen(buf1) >= *l) ? strlen(buf1) : *l) ;
      if ( strcmp(buf1,buf2) == 0) return(0);
    }
  return(1);
}

/*----------------------------------------------------
 * int C2F(graduate)(xmi,xma,xi,xa,np1,np2,kminr,kmaxr,ar)
 * (xgraduate at Scilab level)
 * Rescale an interval so as to find a pretty graduation 
 * for [xmi,xma] given seeks (xi,xa,np1,np2)
 * such that  xi <= xmi <= xmax <= xa 
 * with xi et xa  numbers of type  kminr 10^ar and kmaxr 10^ar.
 * then the interval [xi,xa] can be splited in *np2 sub-intervals
 *  ( kminr-kmaxr can be divided by *np2 ) 
 *  x_i= (kminr + i*(kmaxr-kminr)/ (*np2))*10^ar;
 * i=0:(*np2)
 * ecah of the  np2 intervals can in turn be splited in np1 ungraduated 
 * subintervals 
 * [np1,np2] follow the nax parameters of plot2d.
 *  
 *  We also want to keep np2 small ( *np2 <=10 ) 
 *  and we want [xi,xa] to be as close as possible to the interval  
 *  [xmi,xma]
 *---------------------------------------------------- */

int C2F(graduate)(double *xmi, double *xma, double *xi, double *xa, integer *np1, integer *np2, integer *kminr, integer *kmaxr, integer *ar)
{
  if ( *xmi > *xma) 
    {
      double xma1=*xmi, xmi1=*xma;
      graduate1(&xmi1,&xma1,xi,xa,np1,np2,kminr,kmaxr,ar,0);
    }
  else 
    graduate1(xmi,xma,xi,xa,np1,np2,kminr,kmaxr,ar,0);
  return(0);
}

static void graduate1(double *xmi, double *xma, double *xi, double *xa, integer *np1, integer *np2, integer *kminr, integer *kmaxr, integer *ar, int count)
{
  integer npr,b,i,dx,dxmi,dxma;
  /* fprintf(stderr,"[%20.10f,%20.10f]\n",*xmi,*xma); */
  /* 
   * 
   */
  dx   = ( (*xma) != (*xmi) ) ? (int) ceil(log10(Abs((*xma)-(*xmi)))) :0;
  dxmi = (*xmi != 0 ) ? (int) ceil(log10(Abs((*xmi)))) : 0;
  dxma = (*xma != 0 ) ? (int) ceil(log10(Abs((*xma)))) : 0;
  dx=Max(dx-dxmi,dx-dxma);
  /* il faut limiter b de sorte que dans la decomposition */
  /* avec b les nombres entiers manipules ne deviennent pas trop grands */
  /* on choisit donc b < 10 en considerant que le plus grand entier est */
  /* 0x7FFFFFFF */
  /* on prends aussi un b minimum de 3 : pour avoir des intervalles */
  /* plus serr'es  : ce nombre est 'eventuellement a affiner      */
  b=Max(-dx+2,3);
  /* fprintf(stderr,"choix de b=%d",b); */
  if ( b >= 10 )
    {
      double xmi1,xma1;
      int iexp ;
      /* fprintf(stderr,"je ne peux decomposer les 2 nombres sont identiques\n"); */
      /* 
	a la precision donnee les deux nombre ne peuvent etre decomposer 
	kmin,kmax devrait sinon depasser maxint
	on les ecarte de ce qu'il faut pour pouvoir 
	les separer. 
	Attention : il faut faire attention de bien choisir iexp
	pour ne pas boucler la dedans 
	*/
      iexp = 9 - dxmi -1; 
      xmi1 = *xmi-exp10((double) - iexp);
      xma1 = *xmi+exp10((double) - iexp);
      if ( count > 1 ) 
	{
	  sciprint("Internal Error: Loop in graduate1 \r\n");
	  sciprint("Please send a Bug report to scilab@inria.fr\r\n");
	}
      graduate1(&xmi1,&xma1,xi,xa,np1,np2,kminr,kmaxr,ar,count+1);
      return;
    }
  while ( b >= 1 ) 
    {
      /* fprintf(stderr,"\tAppel avec b=%d\n",b); */
      gradua(xmi,xma,kminr,kmaxr,ar,&npr,&b) ;
      *xi= (*kminr)*exp10((double) *ar);
      *xa= (*kmaxr)*exp10((double) *ar);
      /** fprintf(stderr,"\tRes=[%20.10f,%20.10f]-->[%d,%d,10^%d,%d]\n",*xi,*xa
	      ,*kminr,*kmaxr,*ar,npr); */
      *np2= npr;
      if ( *np2 <= 20 ) 
	break;
      else
	b--;
    }
  /* 
    on veut essayer de ne pas depasser 10 intervalles ( *np2 <= 10) 
    pour les intervalle ou on ecrit un nombre,
    or on peut en avoir jusqu'a 20. On regarde si le nombre d'intervalle 
    est divisible. on aura alors une graduation en np2 pour l'ecriture 
    des nombres et une sous graduation np1 juste avec des tirets.
    */
  *np1= 2 ;
  if ( *np2 <= 10 ) return ;
  /* le nombre est > 10 : s'il est impair on rajoute 1 
     pour diviser par deux */
  if ( *np2 % 2 == 1 ) 
    {
      int step ; 
      step = (*kmaxr-*kminr)/(*np2);
      (*np2)++;
      *kmaxr += step;
      *xa =  (*kmaxr)*exp10((double) *ar);
    }
  /* On recherche des diviseurs a nouveaux pour diminuer le nombre 
     d'intervalles */
  for ( i=2 ; i <=10 ; i++)
    {
      if ( *np2 % i == 0)       
	{
	  *np1=i,*np2 /= i;
	  return;
	}
    }
  *np1=*np2;*np2=1;
}

/*
 *  renvoit kminr,kmaxr et ar tels que 
 *  [kminr*10^ar,kmaxr*10^ar] contient [xmi,xma] 
 *  b est un parametre de decompSup,decompInf 
 *  on doit avoir a l'appel xmi < xma.
 *  le choix se fait entre deux intervalles possibles 
 *  on choisit celui qui est le plus proche de [xmi,xma] 
 *  a condition que (kmaxr-kminr) <= 20 
 *  pour b=1 on sait que (kmaxr-kminr ) <= 20 
 *  20 intervalles au plus ( que l'on obtient si xmin et xmax sont 
 *  de signe opposes sinon c'est 10 )
 */

/* np2, and np1 must be smaller than maxint */

#define DMAX 0xFFFFFFF

static void gradua(double *xmi, double *xma, integer *kminr, integer *kmaxr, integer *ar, integer *npr, integer *b)
{
  double x0=*xmi,x1=*xma,loc;
  integer x0k,x0a;
  integer x1k,x1a;
  integer kmin1,kmax1,a1,np1,kmin2,kmax2,a2,np2,kmin,kmax,a,np;
  decompInf(x0,&x0k,&x0a,*b);
  decompSup(x1,&x1k,&x1a,*b);
  /** special cases **/
  if ( x1 == 0.0 )     {      x1a= x0a;}
  if ( x0 == 0.0 )     {      x0a= x1a;}
  loc = Min( floor(x0*exp10((double) -x1a)),((double)DMAX));
  if ( loc < 0) loc = Max( loc, -((double) DMAX));
  kmin1=(int) loc;
  kmax1=x1k;
  np1= Abs(kmax1-kmin1);
  np1= ( np1 < 0 ) ? DMAX : np1;
  if ( np1 > 10 )
    {
      if  ((np1 % 2) == 0) 
	np1 /=2;
      else 
	{
	  np1++; np1 /= 2;
	  kmax1++;
	}
    }
  a1=x1a;
  /* fprintf(stderr,"\t\tsols : [%d,%d].10^%d,n=%d\t",kmin1,kmax1,a1,np1);  */
  kmin2=x0k;
  loc = Min( ceil( x1*exp10((double) -x0a)),((double)DMAX));
  kmax2=(int) loc ;
  np2 = Abs(kmax2-kmin2);
  np2= ( np2 < 0 ) ? DMAX : np2;
  if ( np2 > 10 ) 
    {
      if ( np2 % 2 == 0)
	np2 /=2;
      else 
	{
	  np2++;
	  kmin2--;
	}
    }
  a2=x0a;
  /* fprintf(stderr,"[%d,%d].10^%d=%d\n",kmin2,kmax2,a2,np2);  */
  if ( np1*exp10((double)a1) < np2*exp10((double) a2) )
    {
      if ( np1 <= 20 ) 
	{
	  kmin=kmin1;	  kmax=kmax1;	  np=np1;	  a=a1;
	}
      else 
	{
	  kmin=kmin2;	  kmax=kmax2;	  np=np2;	  a=a2;
	}
    }
  else 
    {
      if ( np2 <= 20 ) 
	{
	  kmin=kmin2;	  kmax=kmax2;	  np=np2;	  a=a2;
	}
      else 
	{
	  kmin=kmin1;	  kmax=kmax1;	  np=np1;	  a=a1;
	}
    }
  *kminr=kmin;
  *kmaxr=kmax;
  *ar=a;
  *npr=np;
  if ( kmin==kmax ) 
    {
      /* 
       * a la precision demandee les deux [xi,xa] est reduit a un point
       * on elargit l'intervalle
       */
      /* fprintf(stderr,"Arg : kmin=kmax=%d",kmin) ; */
      /* fprintf(stderr," a=%d, x0=%f,x1=%f\n",a,x0,x1); */
      (*kminr)-- ; (*kmaxr)++;*npr=2;
    };
}

/*
 * soit x > 0 reel fixe et b entier fixe : alors il existe un unique couple 
 * (k,a) dans NxZ avec k dans [10^(b-1)+1,10^b] tel que 
 * (k-1)*10^a < x <= k 10^a 
 * donne par  a = ceil(log10(x))-b et k=ceil(x/10^a) 
 * decompSup renvoit xk=k et xa=a
 * si x < 0 alors decompSup(x,xk,xa,b) 
 *    s'obtient par decompInf(-x,xk,xa,b) et xk=-xk 
 * Remarque : la taille de l'entier k obtenu est controle par b 
 * il faut choisir b < 10 pour ne pas depasser dans k l'entier maximum
 */

static void decompSup(double x, integer *xk, integer *xa, integer b)
{
  if ( x == 0.0 ) 
    { 
      *xk=0 ; *xa= 1; /* jpc */
    }
  else 
    {
      if ( x > 0 ) 
	{
	  double xd;
	  static double epsilon; 
	  static int first=0; 
	  if ( first == 0) { epsilon = 10.0*F2C(dlamch)("e",1L); first++ ;}
	  /* if x is very near (k+1)10^a (epsilon machine) 
	   * we increment xk
	   */
	  *xa = (int) ceil(log10(x)) - b ;
	  *xk = (int) ceil(x/exp10((double) *xa));
	  xd = (*xk-1)*exp10((double) *xa);
	  if ( Abs((x-xd)/x) < epsilon ) *xk -= 1;
	}
      else 
	{
	  decompInf(-x,xk,xa,b);
	  *xk = -(*xk);
	}
    }
}
 

/*
 * soit x > 0 alors il existe un unique couple 
 * (k,a) dans NxZ avec k in [10^(b-1),10^b-1] tel que 
 * (k)*10^a <= x < (k+1) 10^a 
 * donne par 
 * a = floor(log10(x))-b+1 et k = floor(x/10^a) 
 * decompInf renvoit xk=k et xa=a
 * si x < 0 alors decompInf(x,xk,xa,b) 
 *    s'obtient par decompSup(-x,xk,xa,b) et xk=-xk 
 */

static void decompInf(double x, integer *xk, integer *xa, integer b)
{
  if ( x == 0.0 ) 
    { 
      *xk=0 ; *xa= 1; /* jpc */
    }
  else 
    {
      if ( x > 0 ) 
	{
	  double xup;
	  static double epsilon; 
	  static int first=0; 
	  if ( first == 0) { epsilon = 10.0*F2C(dlamch)("e",1L); first++ ;}
	  *xa = (int) floor(log10(x)) -b +1 ;
	  *xk = (int) floor(x/exp10((double) *xa));
	  /* if x is very near (k+1)10^a (epsilon machine) 
	   * we increment xk
	   */
	  xup = (*xk+1)*exp10((double) *xa);
	  if ( Abs((x-xup)/x) < epsilon ) *xk += 1;
	}
      else 
	{
	  decompSup(-x,xk,xa,b);
	  *xk = -(*xk);
	}
    }
}
 



/* Francois' algo for Theticks */

void flexpo1(double *x, double *f, double *sg, double *scale)
{
  /*    x = sg*f*scale, sg=+-1; scale=10^n; 10 <= f < 100  */
  double xa, k, un=1;
  *sg=un;  xa=*x;
  if (xa<0) {xa=-xa;*sg=-1;}
  *f=xa;*scale=un;
  if (xa<10) 
    {
      for (k=0;++k;)
	{
	  *scale=*scale/10;
	  *f=*f*10;
	  if (*f >= 10) break;
	}
      return;
    }
  if (xa>100) 
    {
      for (k=0;++k;)
	{
	  *scale=*scale*10;
	  *f=*f/10;
	  if (*f <= 100) break;
	}
      return;
    }
}


void  newbnds(double *xminv,double *xmaxv,double *xmin, double *xmax, double *scale)
{
  double fmin, fmax, sgmin, sgmax, sclmax,sclmin, arguc, arguf, scl;
  flexpo1(xminv,&fmin,&sgmin,&sclmin);
  flexpo1(xmaxv,&fmax,&sgmax,&sclmax);
    if ( ABS(*xmaxv) > ABS(*xminv)) 
    {scl=sclmax;}
  else
    {scl=sclmin;}
  arguc=*xmaxv/scl;arguf=*xminv/scl;
  *xmax=ceil(arguc); *xmin=floor(arguf); *scale=scl;
    }

int gradu(xmin, xmax, grads, nticks, thewidth, tst0, scal)
double *xmin, *xmax, *grads, *thewidth, *scal;
int *nticks, *tst0;
{
  int i1;
  static double f,x,sg,scale;
  static int k, w;

  *tst0 = *xmin == 0;
  x = *xmax - *xmin;
  flexpo1(&x, &f, &sg, &scale);
  for (k = 1; k <= 18; ++k) {
    w = k;
    if (f <= spans[k - 1]) break;
  }
  *nticks = ticks[w - 1];
  *thewidth = width[w - 1];
  *scal=scale;

  grads[0] = *xmin;
  i1 = *nticks - 1;
  for (k = 0; k < i1; ++k) {
    grads[k + 1] = grads[k] + *thewidth * scale;
    if (grads[k + 1] == 0) *tst0=1; 
  }
  return 0;
}


int gradu2(xmax, thewidth, scal)
double *xmax, *thewidth, *scal;
{
  
  static double f,x,sg,scale;
  static int k, w;

  x = *xmax;
  flexpo1(&x, &f, &sg, &scale);
  for (k = 1; k <= 18; ++k) {
    w = k;
    if (f <= spans[k - 1]) break;
  }
  *thewidth = width[w - 1];
  *scal=scale;
  return 0;
}


void grds(xminv, xmaxv, gr, nticks, thewidth, tst0, scal)
     double *xminv, *xmaxv, *gr, *thewidth, *scal;
     int *nticks, *tst0;
{
  double span,width,low,up;
  double nup,nlow;
  int res,k;
  span=*xmaxv-*xminv;
  res=gradu2(&span, thewidth, scal);
  width=*thewidth* *scal;

  nlow= ROUND(*xminv/ width);low=nlow* width;
  nup = ROUND(*xmaxv/ width);up = nup* width;

  if (low>*xminv) {nlow=floor(*xminv/width);low=nlow*width;}
  /* printf("%e %e %e %e %e\n", *xmaxv-up, *scal, nup, width, *thewidth); */
  if (up<*xmaxv) {nup=ceil(*xmaxv/width);up=nup*width;}
  
  *nticks=(int) (nup-nlow+1);
  gr[0]=low;gr[*nticks-1]=up;
  for (k=1; k<*nticks-1; ++k)
    {
      gr[k]=gr[k-1]+width;
    }
}

int agrandir(xmin, xmax, xlow, xup)
     double *xmin, *xmax, *xlow, *xup;
{
  int i1;
  static double work[20], thewidth, scal;
  static int i, j, s, nticks, tst0;

  for (s = 0; s <= 100; ++s) {
    i1 = s;
    for (i = 0; i <= i1; ++i) {
      j = s - i;
      *xup = *xmax + (double) i;
      *xlow = *xmin - (double) j;
      gradu(xlow, xup, work, &nticks, &thewidth, &tst0, &scal);
      if (tst0) {
	return 0;
      }
    }
  }
  return 0;
}


int C2F(theticks)(xminv, xmaxv, grads, ngrads)
     double *xminv, *xmaxv, *grads;
     int *ngrads;
/*   Function used to calculate ticks locations for plotting    *
 *   real values located between xminv and xmaxv.               *
 *   grads is a vector with at most 20 components such that     *
 *   grads(1:ngrads) = linspace(xl, xu, ngrads)                 *
 *   xl <= xminv, xu >= xmaxv;                                  *
 *   If xminv<0 and xmaxv>0 one of the ticks is at zero.        *
 *   Auteur/Copyright FD. J'ai fais ce programme parce que      *
 *   j'en avais marre de pas voir le zero sur les graduations   */

{
  double d1, d2;  int i1;
  static double xmin, xmax, work[20], xlow, thewidth, xup, scale, scal;
  static int k, tst0;

  /*  if ( (ABS(*xminv)+1) == ABS(*xminv)) */ /* Not really necessary and void bug plot2d([10^60 10^60+1])*/
/*     { */
/*       *ngrads=1;grads[0]=*xminv; return 1; */
/*     } */
  if (*xminv != *xminv) {
   *ngrads=1;grads[0]=*xminv; return 1; 
  }
  if (*xmaxv != *xmaxv) {
   *ngrads=1;grads[0]=*xmaxv; return 1; 
  }

  if (*xminv == *xmaxv) {
    xmin=floor(*xminv);xmax=ceil(*xmaxv);
    if (xmin==xmax) {
      xmax=xmax+1;
      xmin=xmin-1;
      *ngrads=3;grads[0]=xmin;grads[1]=xmin+1;grads[2]=xmax;return 1;
    }
    C2F(theticks)(&xmin,&xmax,grads,ngrads);
    return 0;
  }
  if (*xminv >= 0 && *xmaxv > 0) {
    if (*xminv > *xmaxv) {
      xmin=*xmaxv;xmax=*xminv;
      grds(&xmin,&xmax,grads,ngrads, &thewidth, &tst0, &scal);
      return 0;
    }
    grds(xminv, xmaxv, grads, ngrads, &thewidth, &tst0, &scal);
    return 0;
  }
  if (*xminv < 0 && *xmaxv <= 0) {
    d1 = -(*xmaxv);	d2 = -(*xminv);
    if (*xmaxv < *xminv) {d1= -(*xminv); d2 = -(*xmaxv);}
    grds(&d1, &d2, work, ngrads, &thewidth, &tst0, &scal);
    i1 = *ngrads;
    for (k = 0; k < i1; ++k) {
      grads[k] = -work[*ngrads - k -1];
    }
    return 0;
  }
  if (*xminv > 0 && *xmaxv <0)
    {
      /*  should never happen ...   */
      d1=*xmaxv; d2=*xminv;
      C2F(theticks)(&d1, &d2, grads, ngrads);
      return 0;
    }
  newbnds(xminv, xmaxv, &xmin, &xmax, &scale);
  agrandir(&xmin, &xmax, &xlow, &xup);
  gradu(&xlow, &xup, grads, ngrads, &thewidth, &tst0, &scal);
  i1 = *ngrads;
  for (k = 0; k < i1; ++k) {
    grads[k] = scale * grads[k];
  }
  return 0;
} 

/* /\* */
/* link ./theticks.o theticks C */

/* function grads=theticks(xminv,xmaxv) */
/* [grads,ngrads]=call('theticks',xminv,1,'d',xmaxv,2,'d','out',... */
/* [1,40],3,'d',[1,1],4,'i'); */
/* grads=grads(1:ngrads); */
/* endfunction */
 
/* *\/ */


/* I encapsulate C2F(theticks) routine inside TheTicks (this one) because 
   we need to perform a test if the returned grads is a single scalar */

int TheTicks( double *xminv, double * xmaxv, double * grads, int * ngrads)
{
  double tmp = 0.;
  double epsilon = exp10(-15);

  C2F(theticks)(xminv, xmaxv, grads, ngrads);
  
  if(*ngrads == 1)
    {
      /* unfortunately there is only 1 graduation (normally this case 
	 happens when handling small intervals with huge numbers (i.e. [10^60 10^60+1]) */
      /* What I do is to enlarge this interval */
      
      tmp = grads[0];
      grads[0] = (1-epsilon)*tmp;
      grads[1] = tmp;
      grads[2] = (1+epsilon)*tmp;
      
      *ngrads = 3;
    }
  else if(GradEqual(grads,ngrads)==0)
    {
      tmp = grads[0];
      grads[0] = (1-epsilon)*tmp;
      grads[1] = tmp;
      grads[2] = (1+epsilon)*tmp;
      
      *ngrads = 3;
    }
  
  return 0;
}

/* Returns 0 if 2 consecutive grads at least are equal */
int GradEqual(const double grads[],const int *ngrads)
{
  int i;
  const double *g = grads; 
  for( i= 0 ; i < (*ngrads) -1 ; i++)
    {
      if (*g == *(g+1)) return 0;
      g++;
    }
  return 1;
}
