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11.119 Sample ‘stfa’ ¶

Example of stfa.

MGL code:

new a 2000:new b 2000
fill a 'cos(50*pi*x)*(x<-.5)+cos(100*pi*x)*(x<0)*(x>-.5)+\
cos(200*pi*x)*(x<.5)*(x>0)+cos(400*pi*x)*(x>.5)'
subplot 1 2 0 '<_':title 'Initial signal':plot a:axis:xlabel '\i t'
subplot 1 2 1 '<_':title 'STFA plot':stfa a b 64:axis:ylabel '\omega' 0:xlabel '\i t'

C++ code:

void smgl_stfa(mglGraph *gr)	// STFA sample
{
	mglData a(2000), b(2000);
	gr->Fill(a,"cos(50*pi*x)*(x<-.5)+cos(100*pi*x)*(x<0)*(x>-.5)+\
	cos(200*pi*x)*(x<.5)*(x>0)+cos(400*pi*x)*(x>.5)");
	gr->SubPlot(1, 2, 0,"<_");	gr->Title("Initial signal");
	gr->Plot(a);
	gr->Axis();
	gr->Label('x', "\\i t");

	gr->SubPlot(1, 2, 1,"<_");	gr->Title("STFA plot");
	gr->STFA(a, b, 64);
	gr->Axis();
	gr->Label('x', "\\i t");
	gr->Label('y', "\\omega", 0);
}