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Old   July 9, 2001, 17:03
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  #1
lucy
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hello everybody, I got the error: "floating point exception (underflow).

Does anybody know what it means and why it happened?

thanks a lot

lucy
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Old   July 9, 2001, 17:29
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  #2
John C. Chien
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(1). A floating point variable has a range. When the value is less than the minimum range, you get the error message (underflow). (2). If the value is larger than the maximum range, you get the overflow error. (3). You need to review the Fortran language. "it's outside the range".
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Old   July 9, 2001, 17:37
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  #3
lucy
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Do you know why it happened in fluent?

thanks a lot
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Old   July 10, 2001, 12:12
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  #4
Evan Rosenbaum
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Like any computer program, FLUENT has lower and upper numeric thresholds which cannot be exceeded. I'm not sure about UNIX versions, but the PC has both single-precision and double-precision solvers. If you get this message using the single-precision solver, switch to the double-precision solver. If the error goes away, check the result VERY carefully to be sure they make sense. If the error doesn't go away, you certainly have an error somewhere in your model.
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Old   July 11, 2001, 02:57
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Jeremy
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It's a bug: computer programs have bugs. In a code the size of Fluent it is natural. If this happens you just send the case into support and they debug it.
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Old   July 11, 2001, 04:35
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  #6
John C. Chien
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(1). Normally, if it is due to the iteration, then you are likely to get divided by zero or overflow error. (2). If you have a un-defined variable in the code, then sometimes you will get underflow error message. (3). But the exact cause is unknown, unless you can do the debugging and trace it back to the source or location in the code.
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