HP 42S undocumented [MAX] [MIN] functions

[lrdheat]

I am not aware of such functions (would love to find that they are there). Here is a work around (will not work with Nroots involving negative numbers):

LBL “DX”
MVAR X
MVAR H
RCL X
RCL H
COMPLEX
XEQ “FX”
COMPLEX
RTN
END

H (epsilon) of 1E-5 works well

FX is your program of the equation f(x) that you wish to find an extremum.

Finding an extremum consists of solving DX, then executing FX with the number that solving DX placed in the x level of the 4 level stack.