source: Sophya/trunk/SophyaPI/PIGcont/gp_axis.c@ 2243

#include "gp_axis.h"
#include <math.h>
AXIS axis_array[AXIS_ARRAY_SIZE] = AXIS_ARRAY_INITIALIZER(DEFAULT_AXIS_STRUCT);

void dummy(){

  int k=4;
  
}
/*{{{  dbl_raise() used by set_tics */
/* FIXME HBB 20000426: is this really useful? */
static double
dbl_raise(x, y)
double x;
int y;
{
    register int i = abs(y);
    double val = 1.0;

    while (--i >= 0)
        val *= x;

    if (y < 0)
        return (1.0 / val);
    return (val);
}

/*}}} */

/*{{{  set_tic() */
/* the guide parameter was intended to allow the number of tics
 * to depend on the relative sizes of the plot and the font.
 * It is the approximate upper limit on number of tics allowed.
 * But it did not go down well with the users.
 * A value of 20 gives the same behaviour as 3.5, so that is
 * hardwired into the calls to here. Maybe we will restore it
 * to the automatic calculation one day
 */

double
set_tic(l10, guide)
     double l10;
     int guide;
{
    double xnorm, tics, posns;

    int fl = (int) floor(l10);
    xnorm = pow(10.0, l10 - fl);        /* approx number of decades */

    posns = guide / xnorm;      /* approx number of tic posns per decade */

    if (posns > 40)
        tics = 0.05;            /* eg 0, .05, .10, ... */
    else if (posns > 20)
        tics = 0.1;             /* eg 0, .1, .2, ... */
    else if (posns > 10)
        tics = 0.2;             /* eg 0,0.2,0.4,... */
    else if (posns > 4)
        tics = 0.5;             /* 0,0.5,1, */
    else if (posns > 1)
        tics = 1;               /* 0,1,2,.... */
    else if (posns > 0.5)
        tics = 2;               /* 0, 2, 4, 6 */
    else
        /* getting desperate... the ceil is to make sure we
         * go over rather than under - eg plot [-10:10] x*x
         * gives a range of about 99.999 - tics=xnorm gives
         * tics at 0, 99.99 and 109.98  - BAD !
         * This way, inaccuracy the other way will round
         * up (eg 0->100.0001 => tics at 0 and 101
         * I think latter is better than former
         */
        tics = ceil(xnorm);

    return (tics * dbl_raise(10.0, fl));
}
/* this is used in a few places all over the code: undo logscaling of
 * a given range if necessary. If checkrange is TRUE, will int_error() if
 * range is invalid */
void
axis_unlog_interval(axis, min, max, checkrange)
    AXIS_INDEX axis;
    double *min, *max;
    TBOOLEAN checkrange;
{
    if (axis_array[axis].log) {
      if (checkrange && (*min<= 0.0 || *max <= 0.0))printf(" axis_unlog_interval : range must be > 0 !! \n");
          /*int_error(NO_CARET,
                      "%s range must be greater than 0 for log scale",
                      axis_defaults[axis].name);*/
        *min = (*min<=0) ? -VERYLARGE : AXIS_DO_LOG(axis,*min);
        *max = (*max<=0) ? -VERYLARGE : AXIS_DO_LOG(axis,*max);
    }
} 

/*}}} */