1. A program for calculating a tuning parameter for a numerical computation library, the program being arranged to calculate an optimum tuning parameter, based on a preset objective function, for use in executing a numerical computation library, wherein the program causes a computer to execute the steps of: reading the numerical computation library; reading the objective function; setting a user policy as plural policy parameters regarding speed performance and computational accuracy of the numerical computation library; reading, from preset execution histories of numerical computation libraries, execution histories of the numerical computation library; calculating a tuning parameter for the numerical computation library by using the objective function that optimizes, in a domain where the policy parameters are met and based on the execution histories having been read in, the speed performance and computational accuracy constituting two mutually opposing elements; and outputting a calculation result of the objective function.