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acosh.3p (3569B)

    

  1. '\" et
  2. .TH ACOSH "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. acosh,
  12. acoshf,
  13. acoshl
  14. \(em inverse hyperbolic cosine functions
  15. .SH SYNOPSIS
  16. .LP
  17. .nf
  18. #include <math.h>
  19. .P
  20. double acosh(double \fIx\fP);
  21. float acoshf(float \fIx\fP);
  22. long double acoshl(long double \fIx\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 compute the inverse hyperbolic cosine of their
  30. argument
  31. .IR x .
  32. .P
  33. An application wishing to check for error situations should set
  34. .IR errno
  35. to zero and call
  36. .IR feclearexcept (FE_ALL_EXCEPT)
  37. before calling these functions. On return, if
  38. .IR errno
  39. is non-zero or \fIfetestexcept\fR(FE_INVALID | FE_DIVBYZERO |
  40. FE_OVERFLOW | FE_UNDERFLOW) is non-zero, an error has occurred.
  41. .SH "RETURN VALUE"
  42. Upon successful completion, these functions shall return the inverse
  43. hyperbolic cosine of their argument.
  44. .P
  45. For finite values of
  46. .IR x
  47. < 1, a domain error shall occur, and
  48. either a NaN (if supported), or
  49. an implementation-defined value shall be returned.
  50. .P
  51. If
  52. .IR x
  53. is NaN, a NaN shall be returned.
  54. .P
  55. If
  56. .IR x
  57. is +1, +0 shall be returned.
  58. .P
  59. If
  60. .IR x
  61. is +Inf, +Inf shall be returned.
  62. .P
  63. If
  64. .IR x
  65. is \-Inf, a domain error shall occur, and a NaN shall be returned.
  66. .SH ERRORS
  67. These functions shall fail if:
  68. .IP "Domain\ Error" 12
  69. The
  70. .IR x
  71. argument is finite and less than +1.0,
  72. or is \-Inf.
  73. .RS 12 
  74. .P
  75. If the integer expression (\fImath_errhandling\fR & MATH_ERRNO) is
  76. non-zero, then
  77. .IR errno
  78. shall be set to
  79. .BR [EDOM] .
  80. If the integer expression (\fImath_errhandling\fR & MATH_ERREXCEPT) is
  81. non-zero, then the invalid floating-point exception shall be raised.
  82. .RE
  83. .LP
  84. .IR "The following sections are informative."
  85. .SH EXAMPLES
  86. None.
  87. .SH "APPLICATION USAGE"
  88. On error, the expressions (\fImath_errhandling\fR & MATH_ERRNO) and
  89. (\fImath_errhandling\fR & MATH_ERREXCEPT) are independent of each
  90. other, but at least one of them must be non-zero.
  91. .SH RATIONALE
  92. None.
  93. .SH "FUTURE DIRECTIONS"
  94. None.
  95. .SH "SEE ALSO"
  96. .IR "\fIcosh\fR\^(\|)",
  97. .IR "\fIfeclearexcept\fR\^(\|)",
  98. .IR "\fIfetestexcept\fR\^(\|)"
  99. .P
  100. The Base Definitions volume of POSIX.1\(hy2017,
  101. .IR "Section 4.20" ", " "Treatment of Error Conditions for Mathematical Functions",
  102. .IR "\fB<math.h>\fP"
  103. .\"
  104. .SH COPYRIGHT
  105. Portions of this text are reprinted and reproduced in electronic form
  106. from IEEE Std 1003.1-2017, Standard for Information Technology
  107. -- Portable Operating System Interface (POSIX), The Open Group Base
  108. Specifications Issue 7, 2018 Edition,
  109. Copyright (C) 2018 by the Institute of
  110. Electrical and Electronics Engineers, Inc and The Open Group.
  111. In the event of any discrepancy between this version and the original IEEE and
  112. The Open Group Standard, the original IEEE and The Open Group Standard
  113. is the referee document. The original Standard can be obtained online at
  114. http://www.opengroup.org/unix/online.html .
  115. .PP
  116. Any typographical or formatting errors that appear
  117. in this page are most likely
  118. to have been introduced during the conversion of the source files to
  119. man page format. To report such errors, see
  120. https://www.kernel.org/doc/man-pages/reporting_bugs.html .