On 4/27/2012 11:42 PM Debashish Saha said... > 44 sph_yn_P=(l*sph_yn(l,K*R)/(K*R))-sph_yn(l,K*R) Here you're clearly multiplying by R... > ---> 45 Beta_l=l-(K_P*R(sph_jv(l+1,K_P*R))/(sph_jv(l,K_P*R))) ... and here you've got R(...) which is attempting to call R() which isn't defined as a functions and is not callable. Looks like you need to fix your formula. Emile