nan.3 (931B)
1 .TH NAN 3 2 .SH NAME 3 NaN, Inf, isNaN, isInf \- not-a-number and infinity functions 4 .SH SYNOPSIS 5 .B #include <u.h> 6 .br 7 .B #include <libc.h> 8 .PP 9 .ta \w'\fLdouble 'u 10 .B 11 double NaN(void) 12 .PP 13 .B 14 double Inf(int) 15 .PP 16 .B 17 int isNaN(double) 18 .PP 19 .B 20 int isInf(double, int) 21 .SH DESCRIPTION 22 The IEEE floating point standard defines values called 23 `not-a-number' and positive and negative `infinity'. 24 These values can be produced by such things as overflow 25 and division by zero. 26 Also, the library functions sometimes return them when 27 the arguments are not in the domain, or the result is 28 out of range. 29 .PP 30 .I NaN 31 returns a double that is not-a-number. 32 .I IsNaN 33 returns true if its argument is not-a-number. 34 .PP 35 .IR Inf ( i ) 36 returns positive infinity if 37 .I i 38 is greater than or equal to zero, 39 else negative infinity. 40 .I IsInf 41 returns true if its first argument is infinity 42 with the same sign as the second argument. 43 .SH SOURCE 44 .B \*9/src/lib9/nan.c