1D Gaussian lowpass filter

This function returns coefficients of Gaussian lowpass filter.
Advantages of Gaussian filter: no ringing or overshoot in time domain.
Diasadvantage: slow rolloff in frequency domain.
Pass SR=sampling rate, fco=cutoff freq, both in Hz, to the function.
Coefficients for FIR filter of length L (L always odd) are computed.
This symmetric FIR filter of length L=2N+1 has delay N/SR seconds.
Examples of use:
Compute Gaussian filter frequency response when SR=1000,fco=50 Hz:
freqz(gaussfiltcoef(1000,50),1,256,1000);
Filter signal X sampled at 5kHz with Gaussian filter with fco=500:
y=filter(gaussfiltcoef(5000,500),1,X);
SR,fco are not sanity-checked. WCR 2006-10-11.