       delayed function assignment

• To: mathgroup at smc.vnet.net
• Subject: [mg88170] delayed function assignment
• From: leigh <leigh.pascoe at gmail.com>
• Date: Sun, 27 Apr 2008 04:57:43 -0400 (EDT)

```Dear Mathgroup,

I am trying to integrate the pdf of a chi-square mixture distribution.
If I define the pdf as

pdf2 := .25
\!\(pdf2[x] :=  .5*\(\(1/2\^\(1/
2\)\)\/Gamma[1/2]\) \(x\^\(1/2 - 1\)\) \[ExponentialE]\^\(\(-x
\)/
2\) +  .25*\(1\/\(2*Gamma\)\) \[ExponentialE]\^\(\(-x
\)/2\)\)

I can then obtaing the cumulative distribution function symbolically
as

In:=\!\(\$B"i(Bpdf2[x] \[DifferentialD]x\)

Out=\!\(\(-0.25`\)\ 2.718281828459045`\^\(\(-0.5`\)\ x\) + 0.5`\ \
Erf[0.7071067811865476`\ \@x]\)

I can get numerical values using for example

In:=\!\(1 -  .25 - \$B"i(B\_0\%12 pdf2[x] \[DifferentialD]x\)

Out=0.000885691

However if I try to define this as a function of the statistic
obtained, say

\!\(cum2[x] := 1 -  .25 - \$B"i(B\_0\%x pdf2[t] \[DifferentialD]t\)

Then

In:=cum2

Out=cum2

Doesn't evaluate. What should I do to obtain the value as output.