Calculation returning NaN

[Adam B. Fineberg]

I was wondering if someone could point me to a source of information
about the math error NaN.  I understand that this means not a number
but I have been unable to find a reference which explains what causes
this message.  I have a program which uses floating point math
(actually complex math) and several of my results come out as NaN.  I
tried to isolate the problem but when I remove the small section of
code which causes the NaN I get numbers back.  Unfortunately my
program runs for several days and performs about 64 billion
calculations before I get this result.  I have not been succesful in
tracking it down and would appreciate any reference which describes
the conditions which cause NaN since my program ends without errors
and without floating point exceptions.  Thanks in advance for any
help.

Adam B. Fineberg

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* Adam Fineberg                       Center for Computer Aids for    *
* (201) 932-0080 days                 Industrial Productivity (CAIP)  *
* (201) 359-7940 nites                Rutgers University              *
* fineberg at caip.rutgers.edu           Piscataway, New Jersey          *
* fineberg at enterprise.rutgers.edu     08855-1390                      *
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