The Digamma Function

Usage

digamma(z)

Arguments

z Vector argument. May be real or complex but must have positive real part.

Description

Calculates the digamma function, which is the first derivative of the logarithm of the gamma function, for complex vector arguments.

Details

Uses an asymptotic expansion where Re(z) > 5 and a recurrence formula to such a case where Re(z) <= 5. Accuracy is good.

Value

Vector of digamma(z) values.

References

M. Abramowitz and I. A. Stegun (1965) Handbook of Mathematical Functions. Dover.

See Also

trigamma


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