https://docs.oracle.com/cd/E88353_01/html/E37846/cprojf-3m.html
cprojf - man pages section 3: Extended Library Functions, Volume 2
cproj , cprojf , cprojl - complex projection functions These functions compute a projection of z onto the Riemann sphere: z projects to z , except that all...
man pagesextended librarysectionfunctionsvolume