These functions convert between binary strings and decimal numbers like the built-in MATLAB functions BIN2DEC and DEC2BIN but can accommodate negative integers (via two's complement) and fractional positive and negative numbers (via two's complement fixed point with a binary point in the string).
Note that many fractional numbers that can be represented with a finite number of fractional digits cannot be represented by a finite number of fractional bits (specifically non-powers-of-two fractions like 0.3), which means that FIX2DEC will not always exactly invert DEC2FIX.