digamma {MASS}R Documentation

Digamma Function

Description

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

Usage

digamma(z)

Arguments

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

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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