Resample Signal Rate Conversion

Convert a signal between two sample rates by rational resampling, with the anti-alias filtering that makes the result correct rather than merely shorter.

Constraints

• Function: y = resample_signal(x, fs_in, fs_out).
• Reduce the ratio to its lowest terms before resampling.
• Filter at the lower of the two Nyquist frequencies.
• Preserve signal amplitude.
• Reject a non-positive sample rate.
• Report the actual output length.