An embedded control system capable of ensuring precision in arithmetic with data in the floating-point format and also avoiding a shortage of the storage area of a memory is provided.According to an embedded control system in the present invention, when discrete data in the floating-point format is stored in a read-only memory, the discrete data in the floating-point format is converted into data in a significand-reduced floating-point format before being stored. Here, a significand-reduced floating-point number is a number obtained by deleting low-order bits of the significand of a floating-point number. Further, an interpolation search is performed using discrete data, the discrete data in the significand-reduced floating-point format stored in the read-only memory is brought back to the discrete data in the floating-point format before an interpolation search being performed.