Thanks!! This is very helpful! The hope is to generate the same C99 code regardless of the platform. So we need to use a math library that will work across platforms and deliver consistent behaviour.
Ivan On Fri, Apr 22, 2022 at 5:22 AM David Brown <david.br...@hesbynett.no> wrote: > On 22/04/2022 02:18, Ivan Perez wrote: > > Hi, > > > > I'm trying to compile a program for arduino that relies on tgmath.h to > > pick the right version of a function based on the types (the code is > > automatically generated by another tool). > > > > It's failing to compile with avr because tgmath.h is missing. > > > > I thought it was part of the standard C distribution since C99 and thus > > I'd be able to rely on it, but I'm no C expert. Does anyone know why it > > is not included in avr-libc? Any advice? > > > > I'm on Ubuntu 20.04, using: > > avr-libc 2.0.0+Atmel3.6.2-1.1 > > gcc-avr 5.4.0+Atmel3.6.2-1 > > binutils-avr 2.26.20160125+Atmel-3.6.2-2 > > > > Thanks, > > > > Ivan > > You are right that <tgmath.h> has been part of C since C99. But it is > not part of C++, which is what the Arduino tools use. <tgmath.h> has > macros for type-generic maths functions, and was originally implemented > with compiler-specific extensions. With C11, the "_Generic" feature can > be used to make compiler-independent implementations of the functions. > In C++, function overloading has existed from the beginning, and is done > in a completely different way. (Indeed, <tgmath.h> in C was invented to > give C programmers the convenience C++ users already enjoyed for their > maths functions, but made in a C-style manner.) > > So for your C++ code, you should use <cmath>, not <tgmath.h>, and > otherwise the usage will be the same. (You might need a "using > namespace std;", but the Arduino IDE likes to confusingly hide such > detail.) >
