(yes there is just about no room at initial page for the complete list . . . )

x-tan > xtan-derived ::

cxt(x) =def. R( R/x + x/R ) 
sxt(x) =def. R( R/x – x/R ) 
cxs(x) =def. R · cxt(x) / sxt(x) 
sxc(x) =def. R²/cxs(x)

( . . . it the syndrome of the type of bosses who try to save on rubbish while they don't track their spendings on office furniture etc. -- i had an illusion the hackaday was run by normal people -- so much about that)