check s=0.3 r=0.2: Phi(fd)=1.52562136e+00  Psi*q^2E/(E-1)^4=1.52562137e+00
check s=1 r=2: Phi(fd)=1.74721873e+00  Psi*q^2E/(E-1)^4=1.74721854e+00
check s=3 r=0.5: Phi(fd)=2.93198293e-01  Psi*q^2E/(E-1)^4=2.93198252e-01
check s=0.7 r=7: Phi(fd)=2.50815062e+01  Psi*q^2E/(E-1)^4=2.50815071e+01
grid 1500x1501: min Psi = 7.356e-10 ; min Psi/(E q^2 (1+c)) = 4.857e-04 at q=0.001 c=0.7056
any negative: False
