C********************************************************************* SUBROUTINE PYGDIR(X,Q2,P2,AK0,XPGA) C...Purpose: to evaluate the direct contribution, i.e. the C^gamma term, C...as needed in MSbar parametrizations. DIMENSION XPGA(-6:6) DATA PMC/1.3/, PMB/4.6/, AEM2PI/0.0011614/ C...Reset output. DO 100 KFL=-6,6 XPGA(KFL)=0. 100 CONTINUE C...Evaluate common x-dependent expression. XTMP = (X**2+(1.-X)**2) * (-LOG(X)) - 1. CGAM = 3.*AEM2PI*X * (XTMP*(1.+P2/(P2+AK0**2)) + 6.*X*(1.-X)) C...d, u, s part by simple charge factor. XPGA(1)=(1./9.)*CGAM XPGA(2)=(4./9.)*CGAM XPGA(3)=(1./9.)*CGAM C...Also fill for antiquarks. DO 110 KF=1,5 XPGA(-KF)=XPGA(KF) 110 CONTINUE RETURN END