
TRIGAMMAName:
\[ \psi(x) = \frac{\Gamma'(x)} {\Gamma(x)} \] where \( \Gamma \) is the gamma function and \( \Gamma' \) is the derivative of the gamma function. The trigamma function is the derivative of the digamma function and is defined as
This function is defined for positive numbers.
where <x> is a number, variable or a parameter; <y> is a variable or a parameter (depending on what <x> is) where the computed trigamma values are stored; and where the <SUBSET/EXCEPT/FOR qualification> is optional.
LET X2 = TRIGAMMA(X1) LET X2 = TRIGAMMA(X14)
Abramowitz and Stegun, "Handbook of Mathematical Functions, Applied Mathematics Series, Vol. 55", National Bureau of Standards, 1964 (chapter 6).
TITLE CASE ASIS TITLE Trigamma Function PLOT TRIGAMMA(X) FOR X = 0.01 0.01 10  
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Date created: 01/31/2015 