Synopsis
		sfsoftclip < in.rsf > out.rsf upper= lower= sharp=1.0/fmax(upper*upper,lower*lower)

Uses softplus function
Performs lower clipping then upper clipping if both specified

lower clipping:
y = output, x = input, k = sharpness, c = lower clip value
y = ln(1+exp(k*(x-c)))/k + c

upper clipping:
y = output, x = input, k = sharpness, c = upper clip value
y = -ln(1+exp(k*(c-x)))/k + c

Parameters
		float lower=   float sharp=1.0/fmax(upper*upper,lower*lower)   float upper=

Used In
		TCCS          probdif/noisy-synthetic probdif/synthetic