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< c‎ | numeric‎ | math

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Common mathematical functions

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Common mathematical functions

Functions

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abslabsllabsimaxabs

(C99)(C99)

divldivlldivimaxdiv

(C99)(C99)

(C99)

(C99)

(C99)

(C99)

nannanfnanlnandN

(C99)(C99)(C99)(C23)

Maximum/minimum operations

(C99)

(C99)

(C23)

(C23)

(C23)

(C23)

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(C23)

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(C23)

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(C99)

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(C99)(C23)

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(C23)

(C23)

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(C99)

(C99)

(C99)

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roundlroundllround

(C99)(C99)(C99)

(C23)

(C99)

(C99)

rintlrintllrint

(C99)(C99)(C99)

fromfpfromfpxufromfpufromfpx

(C23)(C23)(C23)(C23)

Floating-point manipulation

(C99)(C99)

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nextafternexttoward

(C99)(C99)

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Quantum and quantum exponent

(C23)

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(C23)

(C23)

Decimal re-encoding functions

(C23)

(C23)

(C23)

(C23)

Total order and payload functions

(C23)

(C23)

(C23)

(C23)

Classification

(C99)

(C23)

(C99)

(C99)

(C99)

(C99)

(C99)

(C23)

(C23)

(C99)

(C99)

isless

(C99)

(C99)

(C99)

(C99)

(C23)

(C23)

Error and gamma functions

(C99)

(C99)

(C99)

(C99)

Types

div_tldiv_tlldiv_timaxdiv_t

(C99)(C99)

float_tdouble_t

(C99)(C99)

_Decimal32_t_Decimal64_t

(C23)(C23)

Macro constants

Special floating-point values

HUGE_VALHUGE_VALFHUGE_VALLHUGE_VALDN

(C99)(C99)(C23)

INFINITYDEC_INFINITY

(C99)(C23)

(C99)(C23)

Arguments and return values

FP_ILOGB0FP_ILOGBNAN

(C99)(C99)

FP_NORMALFP_SUBNORMALFP_ZEROFP_INFINITEFP_NAN

(C99)(C99)(C99)(C99)(C99)

FP_LLOGB0FP_LLOGBNAN

(C23)(C23)

FP_INT_UPWARDFP_INT_DOWNWARDFP_INT_TOWARDZEROFP_INT_TONEARESTFROMZEROFP_INT_TONEAREST

(C23)(C23)(C23)(C23)(C23)

Error handling

MATH_ERRNOMATH_ERRNOEXCEPT

(C99)(C99)

math_errhandling

(C99)

Fast operation indicators

FP_FAST_FMAFFP_FAST_FMA

(C99)(C99)

FP_FAST_FADDFP_FAST_FADDLFP_FAST_DADDLFP_FAST_DMADDDN

(C23)(C23)(C23)(C23)

FP_FAST_FMULFP_FAST_FMULLFP_FAST_DMULLFP_FAST_DMMULDN

(C23)(C23)(C23)(C23)

FP_FAST_FFMAFP_FAST_FFMALFP_FAST_DFMALFP_FAST_DMFMADN

(C23)(C23)(C23)(C23)

FP_FAST_FMALFP_FAST_FMADN

(C99)(C23)

FP_FAST_FSUBFP_FAST_FSUBLFP_FAST_DSUBLFP_FAST_DMSUBDN

(C23)(C23)(C23)(C23)

FP_FAST_FDIVFP_FAST_FDIVLFP_FAST_DDIVLFP_FAST_DMDIVDN

(C23)(C23)(C23)(C23)

FP_FAST_FSQRTFP_FAST_FSQRTLFP_FAST_DSQRTLFP_FAST_DMSQRTDN

(C23)(C23)(C23)(C23)

Defined in header <math.h>

#define isless(x, y) /* implementation defined */

(since C99)

Determines if the floating-point number x is less than the floating-point number y, without setting floating-point exceptions.

Contents

1 Parameters
2 Return value
3 Notes
4 Example
5 References
6 See also

[edit] Parameters

x - floating-point value

y - floating-point value

[edit] Return value

Nonzero integral value if x < y, 0 otherwise.

[edit] Notes

The built-in operator< for floating-point numbers may raise FE_INVALID if one or both of the arguments is NaN. This function is a "quiet" version of operator<.

[edit] Example

Run this code

#include <math.h>
#include <stdio.h>
 
int main(void)
{
 printf ("isless(2.0,1.0) = %d\n", isless(2.0, 1.0));
 printf ("isless(1.0,2.0) = %d\n", isless(1.0, 2.0));
 printf ("isless(INFINITY,1.0) = %d\n", isless(INFINITY, 1.0));
 printf ("isless(1.0,NAN) = %d\n", isless(1.0, NAN));
 
 return 0;
}

Possible output:

isless(2.0,1.0) = 0
isless(1.0,2.0) = 1
isless(INFINITY,1.0) = 0
isless(1.0,NAN) = 0

[edit] References

C23 standard (ISO/IEC 9899:2024):

7.12.14.3 The isless macro (p: TBD)

F.10.11 Comparison macros (p: TBD)

C17 standard (ISO/IEC 9899:2018):

7.12.14.3 The isless macro (p: TBD)

F.10.11 Comparison macros (p: TBD)

C11 standard (ISO/IEC 9899:2011):

7.12.14.3 The isless macro (p: 260)

F.10.11 Comparison macros (p: 531)

C99 standard (ISO/IEC 9899:1999):

7.12.14.3 The isless macro (p: 241)

[edit] See also

(C99)

checks if the first floating-point argument is greater than the second
(function macro) [edit]

C++ documentation for isless

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