Is anyone aware of an approximation to the density function for the studentized range distribution https://en.wikipedia.org/wiki/Studentized_range_distribution ? I've found a fast approximation for quantiles made in excel https://www.ars.usda.gov/ARSUserFiles/60540520/RapidCalculationOfQ.pdf And I've found Fortran code for the CDF and another function in the jStat library for cdf values; however I'm curious if there are any coarse approximations for the pdf that are out there - this is to assist in fast plotting of the density curve- it's just a visualization and doesn't need to be too precise.
I appreciate any suggestions anyone has. Thanks!