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C++ API

Function File: irsa_rgenreal.m

[yp,fxp,fyp] = irsa_rgenreal (xp, fmax, arfunc, prfunc)

Generate a real-valued band-limited timeseries with sampling points xp and maximum frequency fmax.

Input:

xp : Vector – sampling points

fmax : Scalar – maximum (band-limiting) frequency

arfunc: String – name of random number generator with desired distribution for the generated frequency amplitudes. Default is randn.

prfunc: String – name of random number generator with desired distribution for the generated frequency phases taken times 2*pi. Default is rand.

The random number generators have to take the number of rows as the first and the number of columns as the second argument.

Output:

yp : Columnvector – sampling values

fxp : Columnvector – frequency points

fyp : Columnvector – frequency values

Demonstration 1

The following code

 N = 32; xp1 = 1.5; ofac = 16;
 xp = irsa_mdsp( 0.01, 0.99, N, "rand" ) + xp1;
 longxp = linspace( 0, N-(1/ofac), N*ofac ) + xp1;
 [yp, fxp, fyp] = irsa_rgenreal( xp, 1/8 ); 
 longyp = irsa_idft( fxp, fyp, longxp, true )*16;
 figure();
 plot( longxp, longyp, '-r', xp, yp, '*b' ); 
 title( "Irregular timeseries with mean spacing 1 and fmax = 1/8" );
 xlabel( "Sampling points" ); 
 ylabel( "Sampling values" );
 legend('off');
 hold on;
 input("Press Enter to see the spectrum up to the band-limit");
 irsa_plotdft( fxp, fyp ); 
 input("Press Enter to see the spectrum via DFT");
 fxp = irsa_dftfp( xp );
 fyp = irsa_dft( xp, yp, fxp );
 irsa_plotdft( fxp, fyp );

Produces the following output

Press Enter to see the spectrum up to the band-limit
Press Enter to see the spectrum via DFT

and the following figure

Figure 1