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Significant digits of variables in CFX

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Old   July 8, 2020, 16:00
Default Significant digits of variables in CFX
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Jerry
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Hi everyone,

I am using the expression in CFX to express a polynomial function with the coefficients of 16 significant digits. It seems that CFX does not read all the significant digits of the coefficient because the calculation result of the expression is incorrect. I am wondering how many significant digits are defaulted in CFX. Is there any chance to modify the significant digits in CFX? If so, how to do it? Thank you!

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Jerry
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Old   July 8, 2020, 17:59
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Do you use double precision?
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Old   July 9, 2020, 03:06
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Quote:
Originally Posted by Gert-Jan View Post
Do you use double precision?
Yes, I did.
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Old   July 9, 2020, 09:46
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Can you share the expression?

I would like to see an expression that requires that many digits to be accurate within engineering limits. What kind of precision is being asked on the left-hand side? Perhaps the expression is not being written in a "less sensitive form" to round off.

Polynomials are supposed to be written using Horner's method or something along those lines to reduce round off as the higher powers come into play.
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Old   July 13, 2020, 13:44
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You could calculate a table in different software, and use this table as a user function in CFX Pre instead of the polynomial fit.
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