How does the reaction-force RPSD (POST26) relate to the 1-sigma reaction force (POST1)?
The reaction force RPSD is the response, in force^2/Hz units, over the frequency range, so if you integrate and take the square root, you should get the same as 1-sigma reactions. Attached is an example:
psdval,1, 1, 1
frms_post26 = sqrt(fpsd(flast))