### 4.1 Mathematical Constants

The library ensures that the standard BSD mathematical constants are defined. For reference, here is a list of the constants:

M_E

The base of exponentials, e

M_LOG2E

The base-2 logarithm of e, \log_2 (e)

M_LOG10E

The base-10 logarithm of e, \log_10 (e)

M_SQRT2

The square root of two, \sqrt 2

M_SQRT1_2

The square root of one-half, \sqrt{1/2}

M_SQRT3

The square root of three, \sqrt 3

M_PI

The constant pi, \pi

M_PI_2

Pi divided by two, \pi/2

M_PI_4

Pi divided by four, \pi/4

M_SQRTPI

The square root of pi, \sqrt\pi

M_2_SQRTPI

Two divided by the square root of pi, 2/\sqrt\pi

M_1_PI

The reciprocal of pi, 1/\pi

M_2_PI

Twice the reciprocal of pi, 2/\pi

M_LN10

The natural logarithm of ten, \ln(10)

M_LN2

The natural logarithm of two, \ln(2)

M_LNPI

The natural logarithm of pi, \ln(\pi)

M_EULER

Euler’s constant, \gamma