5.1.4 libq Library and Fixed-Point Data Format

The functions in the libq library use the fixed-point data format. The parameters passed and the results generated by the functions are fractional in nature. For dsPIC33C/E/F and dsPIC30 devices, there are two similar sets of math functions which perform the same math operations. One set supports Q15 operands and the other supports Q15.16 operands. Q15.16 operand functions, naturally, have better precision and range compared to Q15 operand functions. For dsPIC33A devices, all fixed-point math operations are based on Q1.31 operands.