Exponential Functions

Intel® C++ Compiler Classic Developer Guide and Reference

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Date 3/31/2023

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Exponential Functions

Many routines in the Intel® C++ Compiler Classic Math Library are more optimized for Intel® microprocessors than for non-Intel microprocessors.

The mathimf.h header file includes prototypes for Intel® C++ Compiler Classic Math Library functions.

The math library supports the following exponential functions:

cbrt

Description: The cbrt function returns the cube root of x.

Calling interface:
double cbrt(double x);
long double cbrtl(long double x);
float cbrtf(float x);

exp

Description: The exp function returns e raised to the x power, e^x.

errno: ERANGE, for underflow and overflow conditions

Calling interface:
double exp(double x);
long double expl(long double x);
float expf(float x);

exp10

Description: The exp10 function returns 10 raised to the x power, 10^x.

errno: ERANGE, for underflow and overflow conditions

Calling interface:
double exp10(double x);
long double exp10l(long double x);
float exp10f(float x);

exp2

Description: The exp2 function returns 2 raised to the x power, 2^x.

errno: ERANGE, for underflow and overflow conditions

Calling interface:
double exp2(double x);
long double exp2l(long double x);
float exp2f(float x);

expm1

Description: The expm1 function returns e raised to the x power, minus 1, e^x-1.

errno: ERANGE, for overflow conditions

Calling interface:
double expm1(double x);
long double expm1l(long double x);
float expm1f(float x);

frexp

Description: The frexp function converts a floating-point number x into signed normalized fraction in [1/2, 1) multiplied by an integral power of two. The signed normalized fraction is returned, and the integer exponent stored at location exp.

Calling interface:
double frexp(double x, int *exp);
long double frexpl(long double x, int *exp);
float frexpf(float x, int *exp);

hypot

Description: The hypot function returns the square root of (x² + y²).

errno: ERANGE, for overflow conditions

Calling interface:
double hypot(double x, double y);
long double hypotl(long double x, long double y);
float hypotf(float x, float y);

ilogb

Description: The ilogb function returns the exponent of x base two as a signed int value.

errno: ERANGE, for x = 0

Calling interface:
int ilogb(double x);
int ilogbl(long double x);
int ilogbf(float x);

invsqrt

Description: The invsqrt function returns the inverse square root.

Calling interface:
double invsqrt(double x);
long double invsqrtl(long double x);
float invsqrtf(float x);

ldexp

Description: The ldexp function returns x*2^exp, where exp is an integer value.

errno: ERANGE, for underflow and overflow conditions

Calling interface:
double ldexp(double x, int exp);
long double ldexpl(long double x, int exp);
float ldexpf(float x, int exp);

log

Description: The log function returns the natural log of x, ln(x).

errno: EDOM, for x < 0
errno: ERANGE, for x = 0

Calling interface:
double log(double x);
long double logl(long double x);
float logf(float x);

log10

Description: The log10 function returns the base-10 log of x, log₁₀(x).

errno: EDOM, for x < 0
errno: ERANGE, for x = 0

Calling interface:
double log10(double x);
long double log10l(long double x);
float log10f(float x);

log1p

Description: The log1p function returns the natural log of (x+1), ln(x + 1).

errno: EDOM, for x < -1
errno: ERANGE, for x = -1

Calling interface:
double log1p(double x);
long double log1pl(long double x);
float log1pf(float x);

log2

Description: The log2 function returns the base-2 log of x, log₂(x).

errno: EDOM, for x < 0
errno: ERANGE, for x = 0

Calling interface:
double log2(double x);
long double log2l(long double x);
float log2f(float x);

logb

Description: The logb function returns the signed exponent of x.

errno: EDOM, for x = 0

Calling interface:
double logb(double x);
long double logbl(long double x);
float logbf(float x);

pow

Description: The pow function returns x raised to the power of y, x^y.

errno: EDOM, for x = 0 and y < 0
errno: EDOM, for x < 0 and y is a non-integer
errno: ERANGE, for overflow and underflow conditions

Calling interface:
double pow(double x, double y);
long double powl(double x, double y);
float powf(float x, float y);

pow2o3

Description: The pow2o3 function returns the cube root of x squared, cbrt(x²).

Calling interface:
double pow2o3(double x);
float pow2o3f(float x);

pow3o2

Description: The pow3o2 function returns the square root of the cube of x, sqrt(x³).

errno: EDOM, for x < 0
errno: ERANGE, for overflow and underflow conditions

Calling interface:
double pow3o2(double x);
float pow3o2f(float x);

powr

Description: The powr function returns x raised to the power of y, x^y, where x ≥ 0.

errno: EDOM, for x < 0
errno: ERANGE, for overflow and underflow conditions

Calling interface:
double powr(double x, double y);
float powrf(float x, float y);

scalb

Description: The scalb function returns x*2^y, where y is a floating-point value.

errno: ERANGE, for underflow and overflow conditions

Calling interface:
double scalb(double x, double y);
long double scalbl(long double x, long double y);
float scalbf(float x, float y);

scalbn

Description: The scalbn function returns x*2ⁿ, where n is an integer value.

errno: ERANGE, for underflow and overflow conditions

Calling interface:
double scalbn(double x, int n);
long double scalbnl (long double x, int n);
float scalbnf(float x, int n);

scalbln

Description: The scalbln function returns x*2ⁿ, where n is a long integer value.

errno: ERANGE, for underflow and overflow conditions

Calling interface:
double scalbln(double x, long int n);
long double scalblnl (long double x, long int n);
float scalblnf(float x, long int n);

sqrt

Description: The sqrt function returns the correctly rounded square root.

errno: EDOM, for x < 0

Calling interface:
double sqrt(double x);
long double sqrtl(long double x);
float sqrtf(float x);

Parent topic: Intel® C++ Compiler Classic Math Library

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Intel® C++ Compiler Classic Developer Guide and Reference

Exponential Functions

cbrt

exp

exp10

exp2

expm1

frexp

hypot

ilogb

invsqrt

ldexp

log

log10

log1p

log2

logb

pow

pow2o3

pow3o2

powr

scalb

scalbn

scalbln

sqrt