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frexp.3p (2815B)

    

  1. '\" et
  2. .TH FREXP "3P" 2017 "IEEE/The Open Group" "POSIX Programmer's Manual"
  3. .\"
  4. .SH PROLOG
  5. This manual page is part of the POSIX Programmer's Manual.
  6. The Linux implementation of this interface may differ (consult
  7. the corresponding Linux manual page for details of Linux behavior),
  8. or the interface may not be implemented on Linux.
  9. .\"
  10. .SH NAME
  11. frexp,
  12. frexpf,
  13. frexpl
  14. \(em extract mantissa and exponent from a double precision number
  15. .SH SYNOPSIS
  16. .LP
  17. .nf
  18. #include <math.h>
  19. .P
  20. double frexp(double \fInum\fP, int *\fIexp\fP);
  21. float frexpf(float \fInum\fP, int *\fIexp\fP);
  22. long double frexpl(long double \fInum\fP, int *\fIexp\fP);
  23. .fi
  24. .SH DESCRIPTION
  25. The functionality described on this reference page is aligned with the
  26. ISO\ C standard. Any conflict between the requirements described here and the
  27. ISO\ C standard is unintentional. This volume of POSIX.1\(hy2017 defers to the ISO\ C standard.
  28. .P
  29. These functions shall break a floating-point number
  30. .IR num
  31. into a normalized fraction and an integral power of 2. The integer
  32. exponent shall be stored in the
  33. .BR int
  34. object pointed to by
  35. .IR exp .
  36. .SH "RETURN VALUE"
  37. For finite arguments, these functions shall return the value
  38. .IR x ,
  39. such that
  40. .IR x
  41. has a magnitude in the interval [\(12,1) or 0, and
  42. .IR num
  43. equals
  44. .IR x
  45. times 2 raised to the power *\fIexp\fP.
  46. .P
  47. If
  48. .IR num
  49. is NaN, a NaN shall be returned, and the value of *\fIexp\fP is
  50. unspecified.
  51. .P
  52. If
  53. .IR num
  54. is \(+-0, \(+-0 shall be returned, and the value of *\fIexp\fP shall be
  55. 0.
  56. .P
  57. If
  58. .IR num
  59. is \(+-Inf,
  60. .IR num
  61. shall be returned, and the value of *\fIexp\fP is unspecified.
  62. .SH ERRORS
  63. No errors are defined.
  64. .P
  65. .LP
  66. .IR "The following sections are informative."
  67. .SH EXAMPLES
  68. None.
  69. .SH "APPLICATION USAGE"
  70. None.
  71. .SH RATIONALE
  72. None.
  73. .SH "FUTURE DIRECTIONS"
  74. None.
  75. .SH "SEE ALSO"
  76. .IR "\fIisnan\fR\^(\|)",
  77. .IR "\fIldexp\fR\^(\|)",
  78. .IR "\fImodf\fR\^(\|)"
  79. .P
  80. The Base Definitions volume of POSIX.1\(hy2017,
  81. .IR "\fB<math.h>\fP"
  82. .\"
  83. .SH COPYRIGHT
  84. Portions of this text are reprinted and reproduced in electronic form
  85. from IEEE Std 1003.1-2017, Standard for Information Technology
  86. -- Portable Operating System Interface (POSIX), The Open Group Base
  87. Specifications Issue 7, 2018 Edition,
  88. Copyright (C) 2018 by the Institute of
  89. Electrical and Electronics Engineers, Inc and The Open Group.
  90. In the event of any discrepancy between this version and the original IEEE and
  91. The Open Group Standard, the original IEEE and The Open Group Standard
  92. is the referee document. The original Standard can be obtained online at
  93. http://www.opengroup.org/unix/online.html .
  94. .PP
  95. Any typographical or formatting errors that appear
  96. in this page are most likely
  97. to have been introduced during the conversion of the source files to
  98. man page format. To report such errors, see
  99. https://www.kernel.org/doc/man-pages/reporting_bugs.html .