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Unexpected result from FindRoot

Posted 1 year ago

Dear all,

I recently met a problem when I was trying to do some calculations. The equation is "6.672221.95092Log[1 + 0.21977(p0.5/x)^(1/1.95092)] == 45.396021.01257Log[1 + 1.4128510^-4(p*0.5/(1 - x))^(1/1.01257)", I want to know when p is in the range from 0 to 100 the corresponding values of x. Following is what I have done in Mathematica:

In the export result, I met something strange: enter image description here

Almost all x values are complex numbers. However, suppose I set the p equal to 100; the corresponding x value calculated from WolframAlpha is 0.9798. enter image description here

I think it is related to the starting value, but I don't know how can I fix it.

Thank you very much.

POSTED BY: Chenghua Deng
2 Replies
Posted 1 year ago

Changing the starting value from 0.01 to 0.98 works.

POSTED BY: Jim Baldwin
Posted 1 year ago

Thank you very much

I changed the starting range of x, and it solved my question.

enter image description here

POSTED BY: Chenghua Deng
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