致命错误：在php中调用未定义的函数gmp_sign（）

I have tried to use gmp_sign in my file to find the sign of the value, but i getting an error like call to undefined function with fatal error.

Is it Ubuntu/Linux? Seems like GMP is not installed on the system. Follow these steps:

  1. Installed GMP with apt-get install php5-gmp

  2. Added extension=php_gmp.so to php.ini

You can use gmp_sign as below:

Installed GMP with:

apt-get install php5-gmp

Added:

extension=php_gmp.so to php.ini