Today, I use two softwares to calculate the value of a hypergeometric functions (2F1). One is Mathematica and another is Matlab. But they give me different results. For examples: (1) 2F1(0.5, 1., 1.5, 5) (Pay an attention to the sign of the image part.) Mathematica's result: 0.21520 - 0.70248 i Matlab's result: 0.2152 + 0.7025 i (2) 2F1(2,3,4,5) Mathematica's result: 0.156542+ 0.150796 i Matlab's result: 0.1565 + 0.1508 i Now, I am confused.