newlib/libm/common/isgreater.c

   1 /* isgreater.c:  This file contains no source code, but rather only the
   2  * man-page comments.  All of the documented "functions" are actually macros
   3  * defined in math.h (q.v.).  */
   4 /*
   5 FUNCTION
   6 <<isgreater>>, <<isgreaterequal>>, <<isless>>, <<islessequal>>, <<islessgreater>>, and <<isunordered>>---comparison macros
   7 INDEX
   8         isgreater
   9 INDEX
  10         isgreaterequal
  11 INDEX
  12         isless
  13 INDEX
  14         islessequal
  15 INDEX
  16         islessgreater
  17 INDEX
  18         isunordered
  19
  20 SYNOPSIS
  21         #include <math.h>
  22         int isgreater(real-floating <[x]>, real-floating <[y]>);
  23         int isgreaterequal(real-floating <[x]>, real-floating <[y]>);
  24         int isless(real-floating <[x]>, real-floating <[y]>);
  25         int islessequal(real-floating <[x]>, real-floating <[y]>);
  26         int islessgreater(real-floating <[x]>, real-floating <[y]>);
  27         int isunordered(real-floating <[x]>, real-floating <[y]>);
  28
  29 DESCRIPTION
  30 <<isgreater>>, <<isgreaterequal>>, <<isless>>, <<islessequal>>,
  31 <<islessgreater>>, and <<isunordered>> are macros defined for use in
  32 comparing floating-point numbers without raising any floating-point
  33 exceptions.
  34
  35 The relational operators (i.e. <, >, <=, and >=) support the usual mathematical
  36 relationships between numeric values.  For any ordered pair of numeric
  37 values exactly one of the relationships--less, greater, and equal--is
  38 true.  Relational operators may raise the "invalid" floating-point
  39 exception when argument values are NaNs.  For a NaN and a numeric value, or
  40 for two NaNs, just the unordered relationship is true (i.e., if one or both
  41 of the arguments a NaN, the relationship is called unordered).  The specified
  42 macros are quiet (non floating-point exception raising) versions of the
  43 relational operators, and other comparison macros that facilitate writing
  44 efficient code that accounts for NaNs without suffering the "invalid"
  45 floating-point exception.  In the synopses shown, "real-floating" indicates
  46 that the argument is an expression of real floating type.
  47
  48 Please note that saying that the macros do not raise floating-point
  49 exceptions, it is referring to the function that they are performing.  It
  50 is certainly possible to give them an expression which causes an exception.
  51 For example:
  52 o+
  53 o       NaN < 1.0
  54                 causes an "invalid" exception,
  55 o       isless(NaN, 1.0)
  56                 does not, and
  57 o       isless(NaN*0., 1.0)
  58                 causes an exception due to the "NaN*0.", but not from the
  59 resultant reduced comparison of isless(NaN, 1.0).
  60 o-
  61
  62 RETURNS
  63 @comment Formatting note:  "$@" forces a new line
  64 No floating-point exceptions are raised for any of the macros.@*
  65 The <<isgreater>> macro returns the value of (x) > (y).@*
  66 The <<isgreaterequal>> macro returns the value of (x) >= (y).@*
  67 The <<isless>> macro returns the value of (x) < (y).@*
  68 The <<islessequal>> macro returns the value of (x) <= (y).@*
  69 The <<islessgreater>> macro returns the value of (x) < (y) || (x) > (y).@*
  70 The <<isunordered>> macro returns 1 if either of its arguments is NaN and 0 otherwise.
  71
  72 PORTABILITY
  73 C99, POSIX.
  74
  75 */