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Student Support Forum: 'Problem with Solve and CDF' topicStudent Support Forum > General > "Problem with Solve and CDF"

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david silverman
04/17/01 6:56pm

Hi,

Here's my next problem with the F-distribution. I used:

ftemp=First[fcut/.Solve[1-gamma==CDF[FRatioDistribution[1,Length[x]-Length[used]-1],fcut],fcut]];

as suggested, with Length[x]=920, Length[used]=0. Works great most of the time, but occassionally all I get is an error:

First::''normal'': ''Nonatomic expression expected at position 1 in First[fcut].''

So I ran the expression alone (without the ''ftemp=First['') to see what was being returned and it returned the word 'fcut' if gamma was less than 0.08. So I tried fooling with SetPrecision around the CDF portion, setting it to 30. Now I get answers for 0.05 and 0.06 but still only get 'fcut' for 0.08 and 0.07, everything's OK for 0.09 and above.

In case you need it, I'm using v4 on a pentium III xeon, $MachinePrecision=16

Thanks again,

David

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Subject (listing for 'Problem with Solve and CDF')
Author Date Posted
Problem with Solve and CDF david silver... 04/17/01 6:56pm
Re: Problem with Solve and CDF Henry Lamb 04/18/01 3:26pm
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