PrevUpHomeScilab Reference ManualNext

dlgamma

dlgamma — derivative of gammaln function, psi function

Calling sequence

 y = dlgamma(x)

Parameters

x: real vector
y : real vector with same size.

Description

dlgamma(x) evaluates, at all the elements of x the logarithmic derivative of the gamma function which corresponds also to the derivative of the gammaln function :



         d/dx (gamma(x)) / gamma(x) = d/dx (ln gamma(x))

x must be real. Also known as the psi function.

Examples



dlgamma(0.5)

See also

gamma, gammaln

Author

W. J. Cody (code from Netlib (specfun))

<< diffdouble >>