Polygamma function in cycle

[ptc-4871036]

Good day,

I have a problem with the psi(1,y) function.

y_i are the Maxwell random variables, which I generate.

Program is attached.

I would be happy for your answers.

[StuartBruff]

The Psi function only takes one parameter; try just Psi(y).

Stuart

[VladimirN]

Stuart,

The digamma function, Psi(x), is defined to be the derivative of the natural logarithm of the Gamma function Γ(x).

The polygamma function, Psi(k, x), is defined to be the kth derivative of the Gamma function.

[StuartBruff]

That will teach me to read the documentation instead of just looking at the error message (... well, it won't. Unfortunately, I have never been possessed of 100 % hindsight and am perfectly capable of replicating the same error )

Stuart

[VladimirN]

That's ok.

[RichardJ]

Mathcad has two processors: one for symbolic math, and one for numeric math. The Psi function is only defined for symbolic math. That's easily remedied though.

[ptc-4871036]

U saved me!

That was really easy, this was my first idea but without vectorization...and it didn't work...

Thx a lot one more time