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11.37 Sample ‘dat_diff’ ¶

Example of diff and integrate.

MGL code:

ranges 0 1 0 1 0 1:new a 30 40 'x*y'
subplot 2 2 0:title 'a(x,y)':rotate 60 40:surf a:box
subplot 2 2 1:title 'da/dx':rotate 60 40:diff a 'x':surf a:box
subplot 2 2 2:title '\int da/dx dxdy':rotate 60 40:integrate a 'xy':surf a:box
subplot 2 2 3:title '\int {d^2}a/dxdy dx':rotate 60 40:diff2 a 'y':surf a:box

C++ code:

void smgl_dat_diff(mglGraph *gr)	// differentiate
{
	gr->SetRanges(0,1,0,1,0,1);
	mglData a(30,40);	a.Modify("x*y");
	gr->SubPlot(2,2,0);	gr->Title("a(x,y)");	gr->Rotate(60,40);
	gr->Surf(a);		gr->Box();
	gr->SubPlot(2,2,1);	gr->Title("da/dx");		gr->Rotate(60,40);
	a.Diff("x");		gr->Surf(a);	gr->Box();
	gr->SubPlot(2,2,2);	gr->Title("\\int da/dx dxdy");	gr->Rotate(60,40);
	a.Integral("xy");	gr->Surf(a);	gr->Box();
	gr->SubPlot(2,2,3);	gr->Title("\\int {d^2}a/dxdy dx");	gr->Rotate(60,40);
	a.Diff2("y");	gr->Surf(a);	gr->Box();
}