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1 | .\" Copyright 2004 Andries Brouwer <aeb@cwi.nl>. |
| 2 | .\" | |
| 3 | .\" Permission is granted to make and distribute verbatim copies of this | |
| 4 | .\" manual provided the copyright notice and this permission notice are | |
| 5 | .\" preserved on all copies. | |
| 6 | .\" | |
| 7 | .\" Permission is granted to copy and distribute modified versions of this | |
| 8 | .\" manual under the conditions for verbatim copying, provided that the | |
| 9 | .\" entire resulting derived work is distributed under the terms of a | |
| 10 | .\" permission notice identical to this one. | |
| 11 | .\" | |
| 12 | .\" Since the Linux kernel and libraries are constantly changing, this | |
| 13 | .\" manual page may be incorrect or out-of-date. The author(s) assume no | |
| 14 | .\" responsibility for errors or omissions, or for damages resulting from | |
| 15 | .\" the use of the information contained herein. The author(s) may not | |
| 16 | .\" have taken the same level of care in the production of this manual, | |
| 17 | .\" which is licensed free of charge, as they might when working | |
| 18 | .\" professionally. | |
| 19 | .\" | |
| 20 | .\" Formatted or processed versions of this manual, if unaccompanied by | |
| 21 | .\" the source, must acknowledge the copyright and authors of this work. | |
| 22 | .\" | |
| 23 | .\" Inspired by a page by Walter Harms created 2002-08-10 | |
| 24 | .\" | |
| 25 | .TH ILOGB 3 2004-10-31 "" "Linux Programmer's Manual" | |
| 26 | .SH NAME | |
| 27 | ilogb, ilogbf, ilogbl \- get integer exponent of a floating point value | |
| 28 | .SH SYNOPSIS | |
| 29 | .B #include <math.h> | |
| 30 | .sp | |
| 31 | .BI "int ilogb(double " x ); | |
| 32 | .br | |
| 33 | .BI "int ilogbf(float " x ); | |
| 34 | .br | |
| 35 | .BI "int ilogbl(long double " x ); | |
| 36 | .sp | |
| 37 | Link with \-lm. | |
| 38 | .SH DESCRIPTION | |
| 39 | These functions return the exponent part of their argument | |
| 40 | as a signed integer. When no error occurs, these functions | |
| 41 | are equivalent to the corresponding | |
| 63aa9df0 | 42 | .BR logb () |
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43 | functions, cast to (int). |
| 44 | An error will occur for zero and infinity and NaN, | |
| 45 | and possibly for overflow. | |
| 46 | .\" .SH "RETURN VALUE" | |
| 47 | .\" These functions return the exponent part of their argument | |
| 48 | .\" as a signed integer. | |
| 49 | .SH ERRORS | |
| 50 | In order to check for errors, set | |
| 51 | .I errno | |
| 52 | to zero and call | |
| 53 | .I feclearexcept(FE_ALL_EXCEPT) | |
| 54 | before calling these functions. On return, if | |
| 55 | .I errno | |
| 56 | is non-zero or | |
| 57 | .I fetestexcept(FE_INVALID | FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW) | |
| 58 | is non-zero, an error has occurred. | |
| 59 | .LP | |
| 60 | If an error occurs and | |
| 61 | .I "(math_errhandling & MATH_ERRNO)" | |
| 62 | is non-zero, then | |
| 63 | .I errno | |
| 64 | is set to | |
| 65 | .BR EDOM . | |
| 66 | If an error occurs and | |
| 67 | .I "(math_errhandling & MATH_ERREXCEPT)" | |
| 68 | is non-zero, then the invalid floating-point exception is raised. | |
| 69 | .LP | |
| 70 | A domain error occurs when | |
| 71 | .I x | |
| 72 | is zero or infinite (or too large, or too small) or NaN. | |
| 73 | If | |
| 74 | .I x | |
| 75 | is zero, the constant | |
| 76 | .B FP_ILOGB0 | |
| 77 | is returned. | |
| 78 | .\" glibc: The numeric value is either `INT_MIN' or `-INT_MAX'. | |
| 79 | If | |
| 80 | .I x | |
| 81 | is NaN, the constant | |
| 82 | .B FP_ILOGBNAN | |
| 83 | is returned. | |
| 84 | .\" glibc: The numeric value is either `INT_MIN' or `INT_MAX'. | |
| 85 | If | |
| 86 | .I x | |
| 87 | is infinite (or too large), INT_MAX is returned. | |
| 88 | If | |
| 89 | .I x | |
| 90 | is too small, INT_MIN is returned. | |
| 91 | .SH "CONFORMING TO" | |
| 68e1685c | 92 | C99 |
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93 | .SH "SEE ALSO" |
| 94 | .BR log (3), | |
| 95 | .BR logb (3) |