Re: [Boost-users] Trouble compiling with float128 data type

so how should I complie your example? and for the following code:

#include <iomanip> #include <iostream> #include #include #include #include #include #include

int main() { using boost::multiprecision::float128;

float128 b = 2; std::cout << std::numeric_limits<float128>::digits << std::endl; std::cout << std::numeric_limits<float128>::digits10 << std::endl; std::cout << std::setprecision(std::numeric_limits<float128>::max_digits10) << log(b) << std::endl; constexpr float128 pi = 3.1415926535897932384626433832795028841971693993751058Q; return 0; }

I get:

...

Executing task: g++-11 -g -I/usr/local/Cellar/boost/1.76.0/include/ -I/usr/local/include/ -L/usr/local/Cellar/boost/1.76.0/lib/ -L/usr/local/Cellar/gcc/11.1.0_1/lib/gcc/11/ -L/usr/local/Cellar/gmp/6.2.1/lib/ -L/usr/local/Cellar/mpfr/4.1.0/lib/ -std=gnu++20 -lmpfr -lgmp -lquadmath -lboost_system -lboost_filesystem '-fext-numeric-literals' fs_main.cpp -o main <

Undefined symbols for architecture x86_64: "__Z17quadmath_snprintfPcmPKcz", referenced from: __ZNK5boost14multiprecision8backends16float128_backend3strB5cxx11ElSt13_Ios_Fmtflags in ccGxvsSR.o "__Z4logqg", referenced from: __ZN5boost14multiprecision8backends8eval_logERNS1_16float128_backendERKS2_ in ccGxvsSR.o ld: symbol(s) not found for architecture x86_64 collect2: error: ld returned 1 exit status The terminal process "zsh '-c', 'g++-11 -g -I/usr/local/Cellar/boost/1.76.0/include/ -I/usr/local/include/ -L/usr/local/Cellar/boost/1.76.0/lib/ -L/usr/local/Cellar/gcc/11.1.0_1/lib/gcc/11/ -L/usr/local/Cellar/gmp/6.2.1/lib/ -L/usr/local/Cellar/mpfr/4.1.0/lib/ -std=gnu++20 -lmpfr -lgmp -lquadmath -lboost_system -lboost_filesystem '-fext-numeric-literals' fs_main.cpp -o main'" terminated with exit code: 1.

Thanks Stefano Gragnani

Il giorno 21 lug 2021, alle ore 17:56, Stefano Gragnani ha scritto:

ok things are better but i still get errors:

...

Executing task: g++-11 -g -I/usr/local/Cellar/boost/1.76.0/include/ -I/usr/local/include/ -L/usr/local/Cellar/boost/1.76.0/lib/ -L/usr/local/Cellar/gcc/11.1.0_1/lib/gcc/11/ -L/usr/local/Cellar/gmp/6.2.1/lib/ -L/usr/local/Cellar/mpfr/4.1.0/lib/ -std=gnu++20 -lmpfr -lgmp -lquadmath -lboost_system -lboost_filesystem '-fext-numeric-literals' float128_example.cpp -o main <

float128_example.cpp: In function 'int main()': float128_example.cpp:186:20: error: call of overloaded 'exp(__float128)' is ambiguous 186 | float128 e1 = exp(1.Q); // Note argument to exp is type float128. | ~~~^~~~~ In file included from /usr/local/Cellar/gcc/11.1.0_1/include/c++/11.1.0/cmath:45, from /usr/local/Cellar/boost/1.76.0/include/boost/config/no_tr1/cmath.hpp:21, from /usr/local/Cellar/boost/1.76.0/include/boost/math/tools/config.hpp:19, from /usr/local/Cellar/boost/1.76.0/include/boost/math/cstdfloat/cstdfloat_types.hpp:18, from /usr/local/Cellar/boost/1.76.0/include/boost/cstdfloat.hpp:18, from float128_example.cpp:19: /usr/local/Cellar/gcc/11.1.0_1/lib/gcc/11/gcc/x86_64-apple-darwin20/11.1.0/include-fixed/math.h:376:15: note: candidate: 'double exp(double)' 376 | extern double exp(double); | ^~~ In file included from /usr/local/Cellar/boost/1.76.0/include/boost/config/no_tr1/cmath.hpp:21, from /usr/local/Cellar/boost/1.76.0/include/boost/math/tools/config.hpp:19, from /usr/local/Cellar/boost/1.76.0/include/boost/math/cstdfloat/cstdfloat_types.hpp:18, from /usr/local/Cellar/boost/1.76.0/include/boost/cstdfloat.hpp:18, from float128_example.cpp:19: /usr/local/Cellar/gcc/11.1.0_1/include/c++/11.1.0/cmath:226:3: note: candidate: 'constexpr long double std::exp(long double)' 226 | exp(long double __x) | ^~~ /usr/local/Cellar/gcc/11.1.0_1/include/c++/11.1.0/cmath:222:3: note: candidate: 'constexpr float std::exp(float)' 222 | exp(float __x) | ^~~ The terminal process "zsh '-c', 'g++-11 -g -I/usr/local/Cellar/boost/1.76.0/include/ -I/usr/local/include/ -L/usr/local/Cellar/boost/1.76.0/lib/ -L/usr/local/Cellar/gcc/11.1.0_1/lib/gcc/11/ -L/usr/local/Cellar/gmp/6.2.1/lib/ -L/usr/local/Cellar/mpfr/4.1.0/lib/ -std=gnu++20 -lmpfr -lgmp -lquadmath -lboost_system -lboost_filesystem '-fext-numeric-literals' float128_example.cpp -o main'" terminated with exit code: 1.

Compiling the following example:

#include <iomanip> #include <iostream> #include #include #include #include #include #include

int main() { using boost::multiprecision::float128;

float128 b = 2; std::cout << std::numeric_limits<float128>::digits << std::endl; std::cout << std::numeric_limits<float128>::digits10 << std::endl; std::cout << std::setprecision(std::numeric_limits<float128>::max_digits10) << log(b) << std::endl; constexpr float128 pi = 3.1415926535897932384626433832795028841971693993751058Q; return 0; }

I get:

...

Executing task: g++-11 -g -I/usr/local/Cellar/boost/1.76.0/include/ -I/usr/local/include/ -L/usr/local/Cellar/boost/1.76.0/lib/ -L/usr/local/Cellar/gcc/11.1.0_1/lib/gcc/11/ -L/usr/local/Cellar/gmp/6.2.1/lib/ -L/usr/local/Cellar/mpfr/4.1.0/lib/ -std=gnu++20 -lmpfr -lgmp -lquadmath -lboost_system -lboost_filesystem '-fext-numeric-literals' fs_main.cpp -o main <

Undefined symbols for architecture x86_64: "__Z17quadmath_snprintfPcmPKcz", referenced from: __ZNK5boost14multiprecision8backends16float128_backend3strB5cxx11ElSt13_Ios_Fmtflags in ccGxvsSR.o "__Z4logqg", referenced from: __ZN5boost14multiprecision8backends8eval_logERNS1_16float128_backendERKS2_ in ccGxvsSR.o ld: symbol(s) not found for architecture x86_64 collect2: error: ld returned 1 exit status The terminal process "zsh '-c', 'g++-11 -g -I/usr/local/Cellar/boost/1.76.0/include/ -I/usr/local/include/ -L/usr/local/Cellar/boost/1.76.0/lib/ -L/usr/local/Cellar/gcc/11.1.0_1/lib/gcc/11/ -L/usr/local/Cellar/gmp/6.2.1/lib/ -L/usr/local/Cellar/mpfr/4.1.0/lib/ -std=gnu++20 -lmpfr -lgmp -lquadmath -lboost_system -lboost_filesystem '-fext-numeric-literals' fs_main.cpp -o main'" terminated with exit code: 1.

Note that if I compile the following example without using Boost I have no linking errors with quadmath:

#include #include <iostream> #include #include

int print(const char *label, __float128 r) { int prec = 20; int width = 46; char buf[128];

int n = quadmath_snprintf(buf, sizeof buf, "%+-#*.36Qe", width, r); printf ("%s: %s\n", label, buf); return 0; }

int main () { __float128 x = 3.14159265358979323846264338327950288q; print("value", x); print("log", logq(x)); print("log10", log10q(x)); print("cos", cosq(x)); print("sin", sinq(x)); print("sqrt", sqrtq(x)); }

Executing task: ./es1.out <

value: +3.141592653589793238462643383279502797e+00 log: +1.144729885849400174143427351353058656e+00 log10: +4.971498726941338543512682882908988723e-01 cos: -1.000000000000000000000000000000000000e+00 sin: +8.671810130123781024797044026043352254e-35 sqrt: +1.772453850905516027298167483341145140e+00

The settings are:

"tasks": [ { "label": "Build with g++ 11", "type": "shell", "command": "g++-11", "args": [ "-g", "-std=gnu++20”, "es1.cpp", "-L/usr/local/Cellar/gcc/11.1.0_1/lib/gcc/11/", "-lquadmath", "-o", "es1.out" ], "group": { "kind": "build", "isDefault": true }, "problemMatcher": [] },

...

Il giorno 21 lug 2021, alle ore 13:08, John Maddock via Boost-users mailto:boost-users@lists.boost.org> ha scritto:

On 20/07/2021 18:44, Stefano Gragnani via Boost-users wrote:

...

Hi,

I'm having trouble compiling code that contains float128 data type. I'm using MacOS Big Sur 11.4. Compiler: gcc version 11.1.0 (Homebrew GCC 11.1.0_1)

I have no other problems with Boost, the only problem is when I use float128.

Please note that I have no problem compiling using libquadmath without using Boost using the __float128 data type.

I use Visual Studio Code:

You can manually fix this by defining BOOST_HAS_FLOAT128 on the command line. However, you may still hit other errors as __float128 and quadmath.h aren't really fully supported in ISO C++ mode. The correct fix is to use -std=gnu++20, and then GNU extensions including __float128 are turned on.

HTH, John.

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