| .TH NAN 3 |
| .SH NAME |
| NaN, Inf, isNaN, isInf \- not-a-number and infinity functions |
| .SH SYNOPSIS |
| .B #include <u.h> |
| .br |
| .B #include <libc.h> |
| .PP |
| .ta \w'\fLdouble 'u |
| .B |
| double NaN(void) |
| .PP |
| .B |
| double Inf(int) |
| .PP |
| .B |
| int isNaN(double) |
| .PP |
| .B |
| int isInf(double, int) |
| .SH DESCRIPTION |
| The IEEE floating point standard defines values called |
| `not-a-number' and positive and negative `infinity'. |
| These values can be produced by such things as overflow |
| and division by zero. |
| Also, the library functions sometimes return them when |
| the arguments are not in the domain, or the result is |
| out of range. |
| .PP |
| .I NaN |
| returns a double that is not-a-number. |
| .I IsNaN |
| returns true if its argument is not-a-number. |
| .PP |
| .IR Inf ( i ) |
| returns positive infinity if |
| .I i |
| is greater than or equal to zero, |
| else negative infinity. |
| .I IsInf |
| returns true if its first argument is infinity |
| with the same sign as the second argument. |
| .SH SOURCE |
| .B \*9/src/lib9/nan.c |
