[rrd-developers] Re: rrd_graph patch for nice log gridlines

[Beat Zahnd]

Beat Zahnd wrote:
>
> Is there some rounding in ytr().
> 

There seems to be a problem with 'pixie' in ytr(). 'pixie' is only
defined if 'value' is a NAN?!?!

Regards, Beat

/* translate data values into y coordinates */
double
ytr(image_desc_t *im, double value){
      static double pixie;
      double yval;
      if (isnan(value)){
        if(!im->logarithmic)
          pixie = (double) im->ysize / (im->maxval - im->minval);
        else
          pixie = (double) im->ysize / (log10(im->maxval) -
log10(im->minval));
        yval = im->yorigin;
      } else if(!im->logarithmic) {
        yval = im->yorigin - pixie * (value - im->minval);
      } else {
        if (value < im->minval) {
          yval = im->yorigin;
        } else {
          yval = im->yorigin - pixie * (log10(value) - log10(im->minval));
        }
      }
      /* make sure we don't return anything too unreasonable. GD lib can
         get terribly slow when drawing lines outside its scope. This is
         especially problematic in connection with the rigid option */
      if (! im->rigid) {
        /* keep yval as-is */
      } else if (yval > im->yorigin) {
        yval = im->yorigin+2;
      } else if (yval < im->yorigin - im->ysize){
        yval = im->yorigin - im->ysize - 2;
      }
      return yval;
}


-- 
Beat ZAHND
Physics Institute
University of Bern                   phone  +41 31 631 3466
Sidlerstrasse 5                      fax    +41 31 631 4405
CH-3012 Bern (Switzerland)  mailto:beat.zahnd at phim.unibe.ch

         http://www.phim.unibe.ch/rosina/rosina.html
                  http://rosetta.esa.int/


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