basic/prob-utils.cc:8:37: error: ‘M_PI’ was not declared in this scope

[hammad26]

I am using Cygwin on windows and trying to run this code. On the first step when running "make" command, getting following error.

basic/prob-utils.cc: In function ‘double rand_gaussian(double, double)’:
basic/prob-utils.cc:8:37: error: ‘M_PI’ was not declared in this scope
double z = sqrt(-2log(x1))cos(2M_PIx2);
^~~~
make: *** [Makefile:13: basic/prob-utils.o] Error 1

Can you guide in this regard?

[chuachilog]

you can try to change the M_PI to 3.14159265358979323846