Reference > Methods digamma(x)¶ Definition¶ Double digamma(Number x) Description¶ Returns the Double value of the digamma function for real positive values of x. Returns NaN when x <= 0 Parameter Definition¶ Name Type Description x Number Input value Examples¶ 1 2 3 4Double r1 = digamma(-1); // r1 == NaN Double r2 = digamma(0); // r2 == NaN Double r3 = digamma(1); // r3 == -0.5772156649016036 Double r4 = digamma(2.5D); // r4 == 0.7031566406451024