def funcHrf(varNumVol, varTr):
vecX = np.arange(<NUM_LIT:0>, varNumVol, <NUM_LIT:1>)<EOL>varHrfPeak = <NUM_LIT> / varTr<EOL>varHrfUndr = <NUM_LIT> / varTr<EOL>varSclUndr = <NUM_LIT><EOL>vecHrfPeak = gamma.pdf(vecX, varHrfPeak)<EOL>vecHrfUndr = gamma.pdf(vecX, varHrfUndr)<EOL>vecHrf = vecHrfPeak - varSclUndr * vecHrfUndr<EOL>vecHrf = np.divide(vecHrf, np.max(vecHrf))<EOL>return vecHrf<EOL>
Create double gamma function. Source:
    http://www.jarrodmillman.com/rcsds/lectures/convolution_background.html