foucalc: Add help info about paralyzable/non-paralyzable deadtime

src/data/timing/foucalc.sl

@@ -12,6 +12,7 @@ define foucalc()
 %\qualifier{avgbkg}{array of average background rates for each energy band}
 %\qualifier{numinst}{[\code{=1}] number of activated PCUs on XTE, required for noise correction}
 %\qualifier{deadtime}{[\code{=1e-5}] detector deadtime in seconds}
+%\qualifier{nonparalyzable}{Set this qualifier if the deadtime is non-paralyzable}
 %\qualifier{fmin}{minimum frequency used for RMS calculation}
 %\qualifier{fmax}{maximum frequency used for RMS calculation}
 %\qualifier{RMS}{DEPRECATED, use rms qualifier instead.}
@@ -63,7 +64,7 @@ define foucalc()
 %          non-noise-corrected (raw) and noise-corrected coherence function and its one-sigma uncertainty\n
 %      * \code{lag}, \code{errlag}:
 %          time lag and its one-sigma uncertainty\n
-%\seealso{makepsd, cross_power_density, colacal}
+%\seealso{makepsd, cross_power_density, colacal, psdcorr_zhang}
 %!%-
 {
   variable lc, dimseg;
@@ -188,7 +189,7 @@ define foucalc()
       
       variable sigrms = sqrt( sum(signormpsd[[idxmin:idxmax-1]] * df) );
       variable noirms = sqrt( sum(noinormpsd[[idxmin:idxmax-1]] * df) );
-      variable errrms = sqrt((4.*sigrms^2*noirms^2+2.*noirms^4)/(numseg*length(idx)*sigrms^2));
+      variable errrms = sqrt((2.*sigrms^2*noirms^2+noirms^4)/(2.*numseg*length(idx)*sigrms^2));
       set_struct_field(rmsquant, "sigrms"+istr, sigrms);
       set_struct_field(rmsquant, "errrms"+istr, errrms);
       set_struct_field(rmsquant, "noirms"+istr, noirms);

src/data/timing/psdcorr_zhang.sl

@@ -22,7 +22,12 @@ define psdcorr_zhang(totrate, tseg, dimseg)
 %\function{psdcorr_zhang}
 %\synopsis{Timing Tools: Poisson Noise and Deadtime Correction (Zhang)}
 %\usage{(freq, psd) = psdcorr_zhang(totrate, tseg, dimseg);}
+%\qualifiers{
+%\qualifier{nonparalyzable}{Set this qualifier if the deadtime is non-paralyzable}
+%}
 %\description
+%    The deadtime is assumed to be paralyzable by default.
+%    
 %    Inputs:
 %      totrate - total countrate of all instruments
 %      tseg    - realtime length of the lc segments used for psd calculation