Dear R-Users, besselJ(pi/2, 0) # 0.4720012 besselJ(pi/2, 1E-14) # 0.4720012 besselJ(pi/2, 1E-15) # 4.720012e+14 There seems to be an error in besselJ(pi/2, eps), where eps is close to 0; although besselJ(pi/2, 0) is well behaved. I am not an expert in the field - but it doesn't seem right. Sincerely, Leonard [[alternative HTML version deleted]]