Intel® oneAPI DPC++/C++ Compiler Developer Guide and Reference
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IMF Device Library Miscellaneous Functions
The IMF Device Library supports the following miscellaneous functions:
copysign
Description: The copysign(x, y) function creates value with a given x magnitude and a copying sign of a second value y.
Calling Interfaces:
Default accuracy:
float sycl::ext::intel::math::copysign ( float x, float y ); double sycl::ext::intel::math::copysign ( double x, double y );
fdim
Description: The fdim(x, y) function returns the positive difference value x - y for x > y, or zero for x <= y.
Special Values:
| Argument x | Argument y | Result fdim(y,x) |
|---|---|---|
| any | S/QNAN | QNAN |
| S/QNAN | any | QNAN |
Calling Interfaces:
Default accuracy:
float sycl::ext::intel::math::fdim ( float x, float y ); double sycl::ext::intel::math::fdim ( double x, double y );
fmod
Description: The fmod(x, y) function performs a computation of the modulus function of x with respect to y.
The fmod(x, y) function returns the value x - n·y for the integer n. If y is nonzero, the result has the same sign as x and magnitude less than the magnitude of y. The fmod(x, y) function is similar to remainder excepts that it rounds the internal quotient n towards zero to an integer instead of to the nearest integer.
Special Values:
| Argument x | Argument y | Result fmod(y,x) |
|---|---|---|
| x not S/QNAN | +/-0 | QNAN |
| +/-∞ | y not S/QNAN | QNAN |
| +/-0 | y not 0 or S/QNAN | +/-0 |
| x finite | +/-∞ | x |
| S/QNAN | any | QNAN |
| any | S/QNAN | QNAN |
Calling Interfaces:
Default accuracy:
float sycl::ext::intel::math::fmod ( float x, float y ); double sycl::ext::intel::math::fmod ( double x, double y );
frexp
Description: The frexp(x, exp) function extracts a mantissa and an exponent of a floating-point value.
This 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 is stored at location exp.
Special Values:
| Argument x | Return frexp(x,exp) | Result exp |
|---|---|---|
| +/-0 | +/-0 | 0 |
| +/-∞ | +/-∞ | undef |
| S/QNAN | QNAN | undef |
Calling Interfaces:
Default accuracy:
float sycl::ext::intel::math::frexp ( float x, int* exp ); double sycl::ext::intel::math::frexp ( double x, int* exp );
isfinite
Description: The isfinite(x) function determines if the given floating-point number x has finite value, for example normal, subnormal or zero, but not infinite or not-a-number (NaN).
Special Values:
| Argument x | Result isfinite(x) |
|---|---|
| x finite | +1 |
| +/-∞ or S/QNAN | +0 |
Calling Interfaces:
Default accuracy:
int sycl::ext::intel::math::isfinite ( float x ); int sycl::ext::intel::math::isfinite ( double x );
isinf
Description: The isinf(x) function determines if the given floating-point number x is a positive or negative infinity.
Special Values:
| Argument x | Result isinf(x) |
|---|---|
| +/-∞ | +1 |
| not +/-∞ | +0 |
Calling Interfaces:
Default accuracy:
int sycl::ext::intel::math::isinf ( float x ); int sycl::ext::intel::math::isinf ( double x );
isnan
Description: The isnan(x) function determines if the given floating-point number x is a NaN value.
Special Values:
| Argument x | Result isnan(x) |
|---|---|
| S/QNAN | +1 |
| not S/QNAN | +0 |
Calling Interfaces:
Default accuracy:
int sycl::ext::intel::math::isnan ( float x ); int sycl::ext::intel::math::isnan ( double x );
ldexp
Description: The ldexp(x, exp) multiplies a floating-point value x by the number 2 raised to the exp power.
This function returns x·2^exp result, where exp is an integer value. On binary systems (where FLT_RADIX is 2), the ldexp function is equivalent to scalbn.
Special Values:
| Argument x | Argument exp | Result ldexp(x,exp) |
|---|---|---|
| +/-0 | any | +/-0 |
| +/-∞ | any | +/-∞ |
| any | 0 | x |
Calling Interfaces:
Default accuracy:
float sycl::ext::intel::math::ldexp ( float x, int exp ); double sycl::ext::intel::math::ldexp ( double x, int exp );
modf
Description: The modf(x, intptr) function splits a floating-point x value into fractional and integer parts.
This function breaks down the floating-point value x into fractional and integer parts, each of which has the same sign as x. The signed fractional portion of x is returned. The integer portion is stored as a floating-point value at the intptr pointer.
Special Values:
| Argument x | Return modf(x,exp) | Result intptr |
|---|---|---|
| +/-0 | +/-0 | +/-0 |
| +/-∞ | +/-0 | +/-∞ |
Calling Interfaces:
Default accuracy:
float sycl::ext::intel::math::modf ( float x, float* intptr ); double sycl::ext::intel::math::modf ( double x, double* intptr );
nan
Description: The nan(tagp) function returns a NaN value.
This function returns a representation of a quiet NaN. The argument tagp selects one of the possible representations.
Calling Interfaces:
Default accuracy:
float sycl::ext::intel::math::nanf ( const char* x ); double sycl::ext::intel::math::nan ( const char* x );
nextafter
Description: The nextafter(x, y) function returns the next representable floating-point value after x in the direction of y.
This function calculates the next representable floating-point value following x in the direction of y. For example, if y is greater than x, the nextafter() returns the smallest representable number greater than x. The returned value is independent of the execution device's current rounding mode.
Special Values:
| Argument x | Argument y | Result nextafter(y,x) |
|---|---|---|
| -0 | +0 | +0 |
| +0 | -0 | -0 |
Calling Interfaces:
Default accuracy:
float sycl::ext::intel::math::nextafter ( float x, float y ); double sycl::ext::intel::math::nextafter ( double x, double y );
remainder
Description: The remainder(x, y) function returns the value of x REM y as required by the IEEE754 standard.
The remainder(x, y) function computes the value x - n·y where n is the integer nearest to the exact value of x / y. If two integers are equally close to x / y, n is the even one. If n is zero, it has the same sign as x. The remainder(x, y) function is similar to fmod, except that it rounds the internal quotient n to the nearest integer instead of towards zero to an integer.
Special Values:
| Argument x | Argument y | Result remainder(y,x) |
|---|---|---|
| x not S/QNAN | +/-0 | QNAN |
| +/-∞ | y not S/QNAN | QNAN |
| +/-0 | y not 0 or S/QNAN | +/-0 |
| x finite | +/-∞ | x |
| S/QNAN | any | QNAN |
| any | S/QNAN | QNAN |
Calling Interfaces:
Default accuracy:
float sycl::ext::intel::math::remainder ( float x, float y ); double sycl::ext::intel::math::remainder ( double x, double y );
remquo
Description: The remquo(x, y, quo) function computes floating-point remainder and part of a quotient.
This function computes a floating-point remainder in the same way as the remainder(x, y, quo) function. It also returns a part of a quotient upon division of x by y through the quo pointer. The value quo has the same sign as and may not be the exact quotient, but agrees with the exact quotient in the low order 3 bits that are sufficient to determine the octant of the result within a period.
Special Values:
| Argument x | Argument y | Return remquo(y,x,quo) | Result quo |
|---|---|---|---|
| x not S/QNAN | +/-0 | QNAN | undef |
| +/-∞ | y not S/QNAN | QNAN | undef |
| +/-0 | y not 0 or S/QNAN | +/-0 | 0 |
| x finite | +/-∞ | x | 0 |
| S/QNAN | any | QNAN | undef |
| any | S/QNAN | QNAN | undef |
Calling Interfaces:
Default accuracy:
float sycl::ext::intel::math::remquo ( float x, float y, int* quo ); double sycl::ext::intel::math::remquo ( double x, double y, int* quo );
saturate
Description: The saturate(x) function clamps the input argument x to the [+0.0, 1.0] range.
Special Values:
| Argument x | Result saturate(x) |
|---|---|
| x < +0 | +0 |
| x > +1 | +1 |
| 0 <= x <= 1 | x |
| S/QNAN | +0 |
Calling Interfaces:
Default accuracy:
float sycl::ext::intel::math::saturate ( float x );
scalbn
Description: The scalbn(x, exp) multiplies a floating-point value x by FLT_RADIX raised to the power exp.
This function returns a x·FLT_RADIX^exp result, where exp is an integer value. On binary systems (where FLT_RADIX is 2), the scalbn function is equivalent to ldexp.
Special Values:
| Argument x | Argument exp | Result scalbn(x,exp) |
|---|---|---|
| +/-0 | any | +/-0 |
| +/-∞ | any | +/-∞ |
| any | 0 | x |
Calling Interfaces:
Default accuracy:
float sycl::ext::intel::math::scalbn ( float x, int exp ); double sycl::ext::intel::math::scalbn ( double x, int exp );
signbit
Description: The signbit(x) function determines if the given floating-point number x is negative.
This function detects the sign bit of both finite and infinite values including zeroes, infinities, and NaNs.
Special Values:
| Argument x | Result signbit(x) |
|---|---|
| x neg. | +1 |
| x pos. | +0 |
Calling Interfaces:
Default accuracy:
int sycl::ext::intel::math::signbit ( float x ); int sycl::ext::intel::math::signbit ( double x );