A numerical data transfer section transfers numerical data and its format as input values for computation from a user program system to a library program system, gives it a name, and registers/manages it. In addition, a computation request section transfers information on the content of the computation from the user program system to the library program system. In library program system, a computing method determining section determine the types of library programs to be used and their execution sequence on the basis of the received information on the content of the computation. A computation-result transmitting section transfers results of execution from the library program system to the user program system in accordance with a request from a user. Accordingly, the user of the user program can more easily use library programs without having to pay attention to specific processes carried out by the library program system.