Re: [Plplot-general] Labelling contours by floats

[Jim D. <li...@di...>]

> On Feb 23, 2017, at 7:24 AM, Peter Williams <pet...@nt...> wrote:
> 
> I need to label my contours with floating point values. However, I seem 
> to get strange results.
> I have a simplified example of what occurs in the program below. It 
> draws an ellipse with contour value 1.0e10, i.e. x*x/4 + y*y = 1.0e10. 
> The contour is good. The label is written as 1.0?#???10 where ? stands 
> for a character I cannot recognise in this context. What am I doing wrong?
> 

What is the OS and which version of PLplot are you using?  

> /* Test of labelling contours by floats */
> #include "plplot.h"
> 
> double xMin,xMax,yMin,yMax,dx,dy;
> 
> double f(double x, double y)
> {
>  return x*x/4 + y*y;
> }
> 
> void transform(double i, double j, double *x, double *y, void *psiData)
> {
>  *x = xMin + i*dx; *y = yMin + j*dy;
> }
> 
> int main()
> {
>   int i,j,m,n,nLevels= 1;
>   double x,y,**z;
>   double pLevels[] = {1.0e10};
>   m = 32; n = 16;
>   xMin = -2.5e5; xMax = 2.5e5; yMin = -1.5e5; yMax =1.5e5;
>   dx = (xMax-xMin)/m; dy = (yMax-yMin)/n;
>   plAlloc2dGrid(&z,m+1,n+1);
>   for(i=0; i <= m; i++) for(j=0; j <= n; j++)
>   {
>    transform(i,j,&x,&y,NULL); z[i][j] = f(x,y);
>   }
>   plsfnam("Labelling.ps"); plsori(1);plsdev("ps");plinit(); 
> plenv(xMin,xMax,yMin,yMax,1,0);
>   pl_setcontlabelformat(1,2); pl_setcontlabelparam(0.01,0.5,0.3,1);
> plcont((PLFLT_MATRIX)z,m+1,n+1,1,m,1,n,pLevels,nLevels,transform,NULL);
>   pllab("x","y","Ellipse");
>   plFree2dGrid(z,m+1,n+1);
>   plend();
>   return 1;
> }
> 
> -- 
> Peter Williams
> 
> 
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