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3.9.18 Using options

Command options allow the easy setup of the selected plot by changing global settings only for this plot. Often, options are used for specifying the range of automatic variables (coordinates). However, options allows easily change plot transparency, numbers of line or faces to be drawn, or add legend entries. The sample function for options usage is:

void template(mglGraph *gr)
{
  mglData a(31,41);
  gr->Fill(a,"-pi*x*exp(-(y+1)^2-4*x^2)");

  gr->SubPlot(2,2,0);	gr->Title("Options for coordinates");
  gr->Alpha(true);	gr->Light(true);
  gr->Rotate(40,60);    gr->Box();
  gr->Surf(a,"r","yrange 0 1"); gr->Surf(a,"b","yrange 0 -1");
  if(mini)	return;
  gr->SubPlot(2,2,1);   gr->Title("Option 'meshnum'");
  gr->Rotate(40,60);    gr->Box();
  gr->Mesh(a,"r","yrange 0 1"); gr->Mesh(a,"b","yrange 0 -1; meshnum 5");
  gr->SubPlot(2,2,2);   gr->Title("Option 'alpha'");
  gr->Rotate(40,60);    gr->Box();
  gr->Surf(a,"r","yrange 0 1; alpha 0.7");
  gr->Surf(a,"b","yrange 0 -1; alpha 0.3");
  gr->SubPlot(2,2,3,"<_");  gr->Title("Option 'legend'");
  gr->FPlot("x^3","r","legend 'y = x^3'");
  gr->FPlot("cos(pi*x)","b","legend 'y = cos \\pi x'");
  gr->Box();    gr->Axis(); gr->Legend(2,"");
}

Example of options usage.





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