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Math Constants | Microsoft Docs |
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11/04/2016 |
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article |
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M_PI constant |
M_PI_2 constant |
math constants |
M_2_PI constant |
M_1_PI constant |
M_E constant |
USE_MATH_DEFINES constant |
M_LOG2E constant |
M_LOG10E constant |
M_LN10 constant |
M_SQRT1_2 constant |
_USE_MATH_DEFINES constant |
M_PI_4 constant |
constants, math |
M_2_SQRTPI constant |
M_SQRT2 constant |
M_LN2 constant |
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db533c3f-6ae8-4520-9d35-c8fabbef3529 |
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8 |
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corob-msft |
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corob |
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ghogen |
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cs-cz |
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#define _USE_MATH_DEFINES // for C++
#include <cmath>
#define _USE_MATH_DEFINES // for C
#include <math.h>
Remarks
The following symbols are defined for the values of their indicated expressions:
| Symbol |
Expression |
Value |
| M_E |
e |
2.71828182845904523536 |
| M_LOG2E |
log2(e) |
1.44269504088896340736 |
| M_LOG10E |
log10(e) |
0.434294481903251827651 |
| M_LN2 |
ln(2) |
0.693147180559945309417 |
| M_LN10 |
ln(10) |
2.30258509299404568402 |
| M_PI |
pi |
3.14159265358979323846 |
| M_PI_2 |
pi/2 |
1.57079632679489661923 |
| M_PI_4 |
pi/4 |
0.785398163397448309616 |
| M_1_PI |
1/pi |
0.318309886183790671538 |
| M_2_PI |
2/pi |
0.636619772367581343076 |
| M_2_SQRTPI |
2/sqrt(pi) |
1.12837916709551257390 |
| M_SQRT2 |
sqrt(2) |
1.41421356237309504880 |
| M_SQRT1_2 |
1/sqrt(2) |
0.707106781186547524401 |
Math Constants are not defined in Standard C/C++. To use them, you must first define _USE_MATH_DEFINES and then include cmath or math.h.
The file ATLComTime.h includes math.h when your project is built in Release mode. If you use one or more of the math constants in a project that also includes ATLComTime.h, you must define _USE_MATH_DEFINES before you include ATLComTime.h.
Global Constants