Integral on HP 42S
04-26-2018, 08:10 PM
Post: #1
 lrdheat Senior Member Posts: 855 Joined: Feb 2014
Integral on HP 42S
Just received an HP 42S. What a beautiful calculator!

If I want to integrate a function such as 5th root of x from -2 to 0, is there a way to do so? On the HP 35S, the x root y command is available for this. Is there a work around on the HP 42S? (Of course, there is no problem with x>0!)
04-26-2018, 08:58 PM (This post was last modified: 04-26-2018 08:59 PM by Dieter.)
Post: #2
 Dieter Senior Member Posts: 2,397 Joined: Dec 2013
RE: Integral on HP 42S
(04-26-2018 08:10 PM)lrdheat Wrote:  If I want to integrate a function such as 5th root of x from -2 to 0, is there a way to do so? On the HP 35S, the x root y command is available for this. Is there a work around on the HP 42S? (Of course, there is no problem with x>0!)

Code:
LBL"FX" MVAR"X" RCL"X" SIGN LastX ABS 0,2 y^x x RTN

The true result is –5/6 · 26/5.

Dieter
04-26-2018, 11:28 PM
Post: #3
 lrdheat Senior Member Posts: 855 Joined: Feb 2014
RE: Integral on HP 42S
Outstanding! Tried it on a mixed case that covers negative and positive results on 1/(5 root(x-1)) from 0 to 33. With accuracy of .001, it takes a while, but comes up with 18.73 on fix 2, close to actual value of 18.75

Works faster dividing into 2 integrals, one from 0 to 1, then from 1 to 33.

Thanks!
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