Intel® oneAPI DPC++/C++ Compiler Developer Guide and Reference

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Document Table of Contents
Document Table of Contents x
Intel® oneAPI DPC++/C++ Compiler Developer Guide and Reference
Intel® oneAPI DPC++/C++ Compiler Developer Guide and Reference x
Intel® oneAPI DPC++/C++ Compiler Introduction Compiler Setup Compiler Reference Compilation Optimization and Programming Compatibility and Portability Notices and Disclaimers
Intel® oneAPI DPC++/C++ Compiler Introduction x
Get Help and Support Related Information
Compiler Setup x
Use the Command Line Use Eclipse Use Microsoft Visual Studio
Use the Command Line x
Specify Component Locations Invoke the Compiler Use the Command Line on Windows File Extensions Use Makefiles for Compilation Use CMake with the Compiler Use Compiler Options Specify Compiler Files Convert Projects to Use a Selected Compiler
Use Eclipse x
Add the Compiler to Eclipse Multiversion Compiler Support Use Cheat Sheets Create a Simple Eclipse Project Makefiles Use Intel Libraries with Eclipse
Use Microsoft Visual Studio x
Create a New Project Use the Intel® oneAPI DPC++/C++ Compiler Select the Compiler Version Specify a Base Platform Toolset Use Property Pages Use Intel® Libraries with Microsoft Visual Studio* Include MPI Support Use Code Coverage in Microsoft Visual Studio* Use Profile Guided Optimization in Microsoft Visual Studio* Optimization Reports Dialog Box Help
Dialog Box Help x
Use Intel® oneAPI DPC++/C++ Compiler dialog box Hardware Profile-Guided Optimization dialog box Options: Compilers dialog box Options: Intel Libraries for oneAPI dialog box Options: Converter dialog box Options: Optimization Reports dialog box Options: Profile Guided Optimization dialog box Profile Guided Optimization dialog box Options: Code Coverage dialog box Code Coverage dialog box Code Coverage Settings dialog box
Compiler Reference x
C/C++/SYCL Calling Conventions Compiler Options Floating-Point Operations Attributes Intrinsics Libraries Macros Pragmas Syntactic and Semantic Errors
Compiler Options x
Alphabetical Option List General Rules for Compiler Options What Appears in the Compiler Option Descriptions Optimization Options Advanced Optimization Options Code Generation Options Offload Compilation, OpenMP*, and Parallel Processing Options Interprocedural Optimization Options Profile Guided Optimization Options Optimization Report Options Floating-Point Options Inlining Options Output, Debug, and Precompiled Header Options Preprocessor Options Component Control Options Language Options Data Options Compiler Diagnostic Options Compatibility Options Linking or Linker Options Miscellaneous Options Deprecated and Removed Compiler Options Display Option Information Alternate Compiler Options Portability and GCC-Compatible Warning Options
Optimization Options x
fast fbuiltin, Oi foptimize-sibling-calls GF nolib-inline O Od Ofast Os Ot Ox
Advanced Optimization Options x
ffreestanding, Qfreestanding fjump-tables fvec-peel-loops, Qvec-peel-loops fvec-remainder-loops, Qvec-remainder-loops fvec-with-mask, Qvec-with-mask ipp-link, Qipp-link mno-gather, Qgather- mno-scatter, Qscatter- qactypes, Qactypes qdaal, Qdaal qipp, Qipp qmkl, Qmkl qmkl-ilp64, Qmkl-ilp64 qmkl-sycl-impl, Qmkl-sycl-impl qopt-assume-no-loop-carried-dep, Qopt-assume-no-loop-carried-dep qopt-dynamic-align, Qopt-dynamic-align qopt-for-throughput, Qopt-for-throughput qopt-mem-layout-trans, Qopt-mem-layout-trans qopt-multiple-gather-scatter-by-shuffles, Qopt-multiple-gather-scatter-by-shuffles qopt-prefetch, Qopt-prefetch qopt-prefetch-distance, Qopt-prefetch-distance qopt-prefetch-loads-only, Qopt-prefetch-loads-only qopt-streaming-stores, Qopt-streaming-stores qopt-zmm-usage, Qopt-zmm-usage qtbb, Qtbb unroll, Qunroll vec, Qvec vec-threshold, Qvec-threshold vecabi, Qvecabi
Code Generation Options x
arch ax, Qax EH fasynchronous-unwind-tables fcf-protection, Qcf-protection fdata-sections, Gw fexceptions ffunction-sections, Gy fomit-frame-pointer Gd GR guard Gv m, Qm m64, Qm64 m80387 march masm mauto-arch, Qauto-arch mbranches-within-32B-boundaries, Qbranches-within-32B-boundaries mintrinsic-promote, Qintrinsic-promote momit-leaf-frame-pointer mtune, tune regcall, Qregcall x, Qx xHost, QxHost
Offload Compilation, OpenMP*, and Parallel Processing Options x
device-math-lib fintelfpga fiopenmp, Qiopenmp flink-huge-device-code fno-sycl-libspirv foffload-static-lib fopenmp fopenmp-concurrent-host-device-compile, Qopenmp-concurrent-host-device-compile fopenmp-declare-target-scalar-defaultmap, Qopenmp-declare-target-scalar-defaultmap fopenmp-device-code-split, Qopenmp-device-code-split fopenmp-device-lib fopenmp-max-parallel-link-jobs, Qopenmp-max-parallel-link-jobs fopenmp-target-buffers, Qopenmp-target-buffers fopenmp-target-default-sub-group-size, Qopenmp-target-default-sub-group-size fopenmp-target-loopopt, Qopenmp-target-loopopt fopenmp-target-simd, Qopenmp-target-simd fopenmp-targets, Qopenmp-targets fsycl fsycl-add-default-spec-consts-image fsycl-add-targets fsycl-dead-args-optimization fsycl-device-code-split fsycl-device-lib fsycl-device-obj fsycl-device-only fsycl-early-optimizations fsycl-enable-function-pointers fsycl-esimd-force-stateless-mem fsycl-explicit-simd fsycl-force-target fsycl-help fsycl-host-compiler fsycl-host-compiler-options fsycl-id-queries-fit-in-int fsycl-instrument-device-code fsycl-link fsycl-link-huge-device-code fsycl-link-targets fsycl-max-parallel-link-jobs fsycl-optimize-non-user-code fsycl-pstl-offload fsycl-rdc fsycl-remove-unused-external-funcs fsycl-targets fsycl-unnamed-lambda fsycl-use-bitcode ftarget-compile-fast ftarget-export-symbols ftarget-register-alloc-mode, Qtarget-register-alloc-mode nolibsycl qopenmp, Qopenmp qopenmp-link qopenmp-simd, Qopenmp-simd qopenmp-stubs, Qopenmp-stubs reuse-exe Wno-sycl-strict Xopenmp-target Xs Xsycl-target
Interprocedural Optimization Options x
flto ipo, Qipo
Profile Guided Optimization Options x
fprofile-dwo-dir fprofile-ml-use fprofile-sample-generate fprofile-sample-use
Optimization Report Options x
qopt-report, Qopt-report qopt-report-file, Qopt-report-file qopt-report-stdout, Qopt-report-stdout
Floating-Point Options x
ffp-accuracy, Qfp-accuracy ffp-contract fimf-absolute-error, Qimf-absolute-error fimf-accuracy-bits, Qimf-accuracy-bits fimf-arch-consistency, Qimf-arch-consistency fimf-domain-exclusion, Qimf-domain-exclusion fimf-max-error, Qimf-max-error fimf-precision, Qimf-precision fimf-use-svml, Qimf-use-svml fma, Qfma fp-model, fp fp-speculation, Qfp-speculation ftz, Qftz pc, Qpc
Inlining Options x
fgnu89-inline finline finline-functions
Output, Debug, and Precompiled Header Options x
c debug (Linux*) debug (Windows*) Fa fasm-blocks Fe fno-system-debug Fo Fp fverbose-asm g gdwarf grecord-gcc-switches gsplit-dwarf o S use-msasm Y- Yc Yu Zi, Z7, ZI
Preprocessor Options x
B C D dD, QdD dM, QdM E EP FI H, QH I idirafter imacros iprefix iquote isystem iwithprefix iwithprefixbefore M, QM MD, QMD MF, QMF MG, QMG MM, QMM MMD, QMMD MQ, QMQ MT, QMT nostdinc++ P TP U undef X
Component Control Options x
Qoption
Language Options x
ansi fno-gnu-keywords fno-operator-names fno-rtti fpermissive fshort-enums fsyntax-only, Zs funsigned-char, J std, Qstd strict-ansi vd vmg x (type option) Zc Zg Zp
Data Options x
fcommon fkeep-static-consts, Qkeep-static-consts fmaintain-32-byte-stack-align, Qmaintain-32-byte-stack-align fmath-errno fpack-struct fpic fpie fstack-protector fstack-security-check fvisibility fzero-initialized-in-bss, Qzero-initialized-in-bss GA Gs GS mcmodel Qlong-double
Compiler Diagnostic Options x
w W Wabi Wall Wcheck-unicode-security Wcomment Wdeprecated Werror, WX Werror-all Wextra-tokens Wformat Wformat-security Wmain Wmissing-declarations Wmissing-prototypes Wpointer-arith Wreorder Wreturn-type Wshadow Wsign-compare Wstrict-aliasing Wstrict-prototypes Wtrigraphs Wuninitialized Wunknown-pragmas Wunused-function Wunused-variable Wwrite-strings
Compatibility Options x
gcc-toolchain vmv
Linking or Linker Options x
F (Windows*) fixed fortlib fuse-ld l L LD MD MT nodefaultlibs no-intel-lib, Qno-intel-lib nostartfiles nostdlib pie pthread shared shared-intel shared-libgcc static static-intel static-libgcc static-libstdc++ T u (Linux*) v Wa Wl, link Wp Xlinker Zl
Miscellaneous Options x
dryrun dumpmachine dumpversion fpreview-breaking-changes help nologo save-temps, Qsave-temps showIncludes sox, Qsox sysroot Tc TC Tp version
Floating-Point Operations x
Programming Tradeoffs in Floating-Point Applications Floating-Point Optimizations Denormal Numbers Floating-Point Environment Set the FTZ and DAZ Flags Tuning Performance IEEE Floating-Point Operations
Attributes x
align align_value allow_cpu_features code_align const cpu_dispatch, cpu_specific target
Libraries x
Create Libraries Use Intel Shared Libraries Manage Libraries Redistribute Libraries When Deploying Applications Resolve References to Shared Libraries Redistributable Library Considerations Intel's Memory Allocator Library SIMD Data Layout Templates Intel® C++ Class Libraries Intel's C++ Asynchronous I/O Extensions for Windows IEEE 754-2008 Binary Floating-Point Conformance Library Intel's Numeric String Conversion Library
SIMD Data Layout Templates x
Function Calls and Containers User-Level Interface Examples
Function Calls and Containers x
Construct an n_container Bounds
User-Level Interface x
SDLT Primitives soa1d_container aos1d_container n_container Bounds Accessors Proxy Objects Number Representation Indexes Convenience and Correctness
aos1d_container x
access_by
n_container x
Layouts Shape make_ n_container template function extent_d template function
Shape x
n_extent_generator
Bounds x
bounds_t sdlt::bounds Template Function n_bounds_t n_bounds_generator bounds_d Template Function
Accessors x
soa1d_container::accessor and aos1d_container::accessor soa1d_container::const_accessor and aos1d_container::const_accessor Accessor Concept
Proxy Objects x
Proxy ConstProxy
Number Representation x
aligned_offset fixed_offset
Indexes x
linear_index n_index_t n_index_generator index_d template function
Convenience and Correctness x
max_val min_val
Examples x
Efficiency with Structure of Arrays Example Complex SDLT Primitive Construction Example Forward Dependency Example Use of Offsets and Methods on a SDLT Primitive Example RGB to YUV Conversion Example
Intel® C++ Class Libraries x
C++ Classes and SIMD Operations Capabilities of C++ SIMD Classes Integer Vector Classes Floating-Point Vector Classes Classes Quick Reference Programming Example Intel's valarray Implementation
Integer Vector Classes x
Terms and Syntax Rules for Operators Assignment Operator Logical Operators Addition and Subtraction Operators Multiplication Operators Shift Operators Comparison Operators Conditional Select Operators Debug Operations Unpack Operators Pack Operators Clear MMX™ State Operator Integer Functions for Intel® Streaming SIMD Extensions Conversions between Fvec and Ivec
Floating-Point Vector Classes x
Fvec Syntax and Notation Data Alignment Conversions Constructors and Initialization Arithmetic Operators Minimum and Maximum Operators Logical Operators Compare Operators Conditional Select Operators for Fvec Classes Cacheability Support Operators Debug Operations Load and Store Operators Unpack Operators Move Mask Operators
Intel's C++ Asynchronous I/O Extensions for Windows x
Intel's C++ Asynchronous I/O Library for Windows Intel's C++ Asynchronous I/O Class for Windows
Intel's C++ Asynchronous I/O Library for Windows x
aio_read aio_write Example for aio_read and aio_write Functions aio_suspend Example for aio_suspend Function aio_error aio_return Example for aio_error and aio_return Functions aio_fsync aio_cancel Example for aio_cancel Function lio_listio Example for lio_listio Function Asynchronous I/O Function Errors
Intel's C++ Asynchronous I/O Class for Windows x
Template Class async_class get_last_operation_id wait get_status get_last_error get_error_operation_id stop_queue resume_queue clear_queue Example for Using async_class Template Class
IEEE 754-2008 Binary Floating-Point Conformance Library x
Intel® IEEE 754-2008 Binary Floating-Point Conformance Library and Usage Function List Homogeneous General-Computational Operations Functions General-Computational Operation Functions Quiet-Computational Operations Functions Signaling-Computational Operations Functions Non-Computational Operations Functions
Intel's Numeric String Conversion Library x
Use Intel's Numeric String Conversion Library Function List
Macros x
ISO Standard Predefined Macros Additional Predefined Macros Use Predefined Macros to Specify Intel® Compilers
Pragmas x
Intel-Specific Pragma Reference Supported OpenMP* Pragmas Pragmas Compatible with Other Compilers
Intel-Specific Pragma Reference x
block_loop/noblock_loop distribute_point inline, noinline, forceinline ivdep loop_count nofusion novector omp target variant dispatch ompx prefetch data prefetch/noprefetch unroll/nounroll unroll_and_jam/nounroll_and_jam vector
Compilation x
Compilation Overview Supported Environment Variables Pass Options to the Linker Specify Alternate Tools Use Configuration Files Use Response Files Global Symbols and Visibility Attributes for Linux* Save Compiler Information in Your Executable Link Debug Information Ahead of Time Compilation Device Offload Compilation Considerations Use a Third-Party Compiler as a Host Compiler for SYCL Code
Optimization and Programming x
Extensions OpenMP* Support Intel® oneAPI Level Zero Vectorization Instrumented Profile-Guided Optimization Hardware Profile-Guided Optimization High-Level Optimization Interprocedural Optimization Methods to Optimize Code Size Compiler Math Library IMF Device Library Basic Arithmetic Operations and Simple Math Functions
OpenMP* Support x
Add OpenMP* Support Parallel Processing Model Worksharing Using OpenMP* Control Thread Allocation OpenMP* Library Support OpenMP* Contexts OpenMP* Advanced Issues OpenMP* Implementation-Defined Behaviors OpenMP* Examples
OpenMP* Library Support x
OpenMP* Runtime Library Routines Intel® Compiler Extension Routines to OpenMP* OpenMP* Support Libraries Use the OpenMP Libraries Thread Affinity Interface OpenMP* Memory Spaces and Allocators
OpenMP* Contexts x
OpenMP* Context Selectors Score and Match Context Selectors
Intel® oneAPI Level Zero x
Intel® oneAPI Level Zero Switch Intel® oneAPI Level Zero Backend Specification Programming with the Intel® oneAPI Level Zero Backend
Vectorization x
Automatic Vectorization Explicit Vector Programming
Automatic Vectorization x
Vectorization Programming Guidelines Use Automatic Vectorization Vectorization and Loops Loop Constructs
Explicit Vector Programming x
User-Mandated or SIMD Vectorization SIMD-Enabled Functions SIMD-Enabled Function Pointers Function Annotations and the SIMD Directive for Vectorization Explicit SIMD SYCL Extension
Interprocedural Optimization x
Use Interprocedural Optimization Performance Considerations Create a Library from IPO Objects Inline Expansion of Functions
Compiler Math Library x
Use the Compiler Math Library Math Function List Trigonometric Functions Hyperbolic Functions Exponential Functions Special Functions Nearest Integer Functions Remainder Functions Miscellaneous Functions copysign fabs fdim finite fma fmax fmin fpclassify isfinite isgreater isgreaterequal isinf isless islessequal islessgreater isnan isnormal isunordered maxmag minmag nan nextafter nexttoward signbit significand Complex Functions C99 Macros
IMF Device Library x
IMF Device Library Usage Example IMF Device Library Function List IMF Device Library Trigonometric Functions IMF Device Library Hyperbolic Functions IMF Device Library Exponential Functions IMF Device Library Logarithmic Functions IMF Device Library Power Functions IMF Device Library Special Functions IMF Device Library Rounding Functions IMF Device Library Miscellaneous Functions
Compatibility and Portability x
Standards Conformance GCC Compatibility and Interoperability Microsoft Compatibility Port from Microsoft Visual C++* to the Intel® oneAPI DPC++/C++ Compiler Port from GCC* to the Intel® oneAPI DPC++/C++ Compiler
Port from Microsoft Visual C++* to the Intel® oneAPI DPC++/C++ Compiler x
Modify Your makefile Other Considerations
Port from GCC* to the Intel® oneAPI DPC++/C++ Compiler x
Modify Your makefile Other Considerations
Intel® oneAPI DPC++/C++ Compiler Developer Guide and Reference

Miscellaneous Functions

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

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

The math library supports the following miscellaneous functions:

NOTE:

FP16 Math Functions have the following requirements:

  • Version 2021.4 or higher of the Intel® oneAPI DPC++/C++ Compiler.

  • A next-generation Intel® Xeon® Scalable processor, code name Sapphire Rapids.

copysign

Description: The copysign function returns the value with the magnitude of x and the sign of y.

Calling interface:
double copysign(double x, double y);
long double copysignl(long double x, long double y);
float copysignf(float x, float y);
_Float16 copysignf16(_Float16 x, _Float16 y);

fabs

Description: The fabs function returns the absolute value of x.

Calling interface:
double fabs(double x);
long double fabsl(long double x);
float fabsf(float x);
_Float16 fabsf16(_Float16 x);

fdim

Description: The fdim function returns the positive difference value, x-y (for x > y) or +0 (for x <= to y).

errno: ERANGE, for overflow conditions

Calling interface:
double fdim(double x, double y);
long double fdiml(long double x, long double y);
float fdimf(float x, float y);
_Float16 fdimf16(_Float16 x, _Float16 y);

finite

Description: The finite function returns 1 if x is not a NaN or +/- infinity. Otherwise 0 is returned.

Calling interface:
int finite(double x);
int finitel(long double x);
int finitef(float x);
int finitef16(_Float16 x);

fma

Description: The fma functions return (x*y)+z.

Calling interface:
double fma(double x, double y, double z);
long double fmal(long double x, long double y, long double z);
float fmaf(float x, float y, float z);
_Float16 fmaf16(_Float16 x, _Float16 y, _Float16 z);

fmax

Description: The fmax function returns the maximum numeric value of its arguments.

Calling interface:
double fmax(double x, double y);
long double fmaxl(long double x, long double y);
float fmaxf(float x, float y);
_Float16 fmaxf16(_Float16 x, _Float16 y);

fmin

Description: The fmin function returns the minimum numeric value of its arguments.

Calling interface:
double fmin(double x, double y);
long double fminl(long double x, long double y);
float fminf(float x, float y);
_Float16 fminf16(_Float16 x, _Float16 y);

fpclassify

Description: The fpclassify function returns the value of the number classification macro appropriate to the value of its argument. Possible values are:

  • 0 (NaN)
  • 1 (Infinity)
  • 2 (Zero)
  • 3 (Subnormal)
  • 4 (Finite)

Calling interface:
int fpclassify(double x);
int fpclassifyl(long double x);
int fpclassifyf(float x);
int fpclassifyf16(_Float16 x);

isfinite

Description: The isfinite function returns 1 if x is not a NaN or +/- infinity. Otherwise 0 is returned.

Calling interface:
int isfinite(double x);
int isfinitel(long double x);
int isfinitef(float x);
int isfinitef16(_Float16 x);

isgreater

Description: The isgreater function returns 1 if x is greater than y. This function does not raise the invalid floating-point exception.

Calling interface:
int isgreater(double x, double y);
int isgreaterl(long double x, long double y);
int isgreaterf(float x, float y);
int isgreaterf16(_Float16 x, _Float16 y);

isgreaterequal

Description: The isgreaterequal function returns 1 if x is greater than or equal to y. This function does not raise the invalid floating-point exception.

Calling interface:
int isgreaterequal(double x, double y);
int isgreaterequall(long double x, long double y);
int isgreaterequalf(float x, float y);
int isgreaterequalf16(_Float16 x, _Float16 y);

isinf

Description: The isinf function returns a non-zero value if and only if its argument has an infinite value.

Calling interface:
int isinf(double x);
int isinfl(long double x);
int isinff(float x);
int isinff16(_Float16 x);

isless

Description: The isless function returns 1 if x is less than y. This function does not raise the invalid floating-point exception.

Calling interface:
int isless(double x, double y);
int islessl(long double x, long double y);
int islessf(float x, float y);
int islessf16(_Float16 x, _Float16 y);

islessequal

Description: The islessequal function returns 1 if x is less than or equal to y. This function does not raise the invalid floating-point exception.

Calling interface:
int islessequal(double x, double y);
int islessequall(long double x, long double y);
int islessequalf(float x, float y);
int islessequalf16(_Float16 x, _Float16 y);

islessgreater

Description: The islessgreater function returns 1 if x is less than or greater than y. This function does not raise the invalid floating-point exception.

Calling interface:
int islessgreater(double x, double y);
int islessgreaterl(long double x, long double y);
int islessgreaterf(float x, float y);
int islessgreaterf16(_Float16 x, _Float16 y);

isnan

Description: The isnan function returns a non-zero value, if and only if x has a NaN value.

Calling interface:
int isnan(double x);
int isnanl(long double x);
int isnanf(float x);
int isnanf16(_Float16 x);

isnormal

Description: The isnormal function returns a non-zero value, if and only if x is normal.

Calling interface:
int isnormal(double x);
int isnormall(long double x);
int isnormalf(float x);
int isnormalf16(_Float16 x);

isunordered

Description: The isunordered function returns 1 if either x or y is a NaN. This function does not raise the invalid floating-point exception.

Calling interface:
int isunordered(double x, double y);
int isunorderedl(long double x, long double y);
int isunorderedf(float x, float y);
int isunorderedf16(_Float16 x, _Float16 y);

maxmag

Description: The maxmag function returns the value of larger magnitude from among its two arguments, x and y. If |x| > |y| it returns x; if |y| > |x| it returns y; otherwise it behaves like fmax(x,y).

Calling interface:
double maxmag(double x, double y);
float maxmagf(float x, float y);
_Float16 maxmagf16(_Float16 x, _Float16 y);

minmag

Description: The minmag function returns the value of smaller magnitude from among its two arguments, x and y. If |x| < |y| it returns x; if |y| < |x| it returns y; otherwise it behaves like fmin(x,y).

Calling interface:
double minmag(double x, double y);
float minmagf(float x, float y);
_Float16 maxmagf16(_Float16 x, _Float16 y);

nan

Description: The nan function returns a quiet NaN, with content indicated through tagp.

Calling interface:
double nan(const char *tagp);
long double nanl(const char *tagp);
float nanf(const char *tagp);
_Float16 nanf16(const char *tagp);

nextafter

Description: The nextafter function returns the next representable value in the specified format after x in the direction of y.

errno: ERANGE, for overflow and underflow conditions

Calling interface:
double nextafter(double x, double y);
long double nextafterl(long double x, long double y);
float nextafterf(float x, float y);
_Float16 nextafterf16(_Float16 x, _Float16 y);

nexttoward

Description: The nexttoward function returns the next representable value in the specified format after x in the direction of y. If x equals y, then the function returns y converted to the type of the function. Use the Qlong-double option on Windows operating systems for accurate results.

errno: ERANGE, for overflow and underflow conditions

Calling interface:
double nexttoward(double x, long double y);
long double nexttowardl(long double x, long double y);
float nexttowardf(float x, long double y);
_Float16 nexttowardf16(_Float16 x, long double y);

signbit

Description: The signbit function returns a non-zero value, if and only if the sign of x is negative.

Calling interface:
int signbit(double x);
int signbitl(long double x);
int signbitf(float x);

significand

Description: The significand function returns the significand of x in the interval [1,2). For x equal to zero, NaN, or +/- infinity, the original x is returned.

Calling interface:
double significand(double x);
long double significandl(long double x);
float significandf(float x);
_Float16 significandf16(_Float16 x);

Parent topic: Compiler Math Library
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