hp prime simple integration doesn't work right...
07-11-2017, 02:44 AM
Post: #1
 webmasterpdx Senior Member Posts: 541 Joined: Sep 2015
hp prime simple integration doesn't work right...
I was trying to do a simple integral from 0 to infinity and it gives me a cryptic message I don't understand about antiderivatives. It gives me the correct answer when I click on enter a second time as long as I do an assume(a>0) first.
Here are the screen captures....
here is a collection of screen captures....attached below.
1. first time run assume(a>0) followed by the integral.

2. After hitting enter, the cryptic message.

3. Hitting enter again and getting the right answer of 1/a.

is there some commands i need to enter first apart from the assume to make this work without the cryptic message.
Thx
-D
07-11-2017, 04:02 AM (This post was last modified: 07-11-2017 04:04 AM by Helge Gabert.)
Post: #2
 Helge Gabert Senior Member Posts: 467 Joined: Dec 2013
RE: hp prime simple integration doesn't work right...
I thought Bernard replied well to your OP. Definite integration with symbolic variables with bounds involving infinity is problematic because checking for continuity between the bounds is not trivial. This is also a problem for expressions with symbolic variables in solve, as discussed in this older thread,

(Example 2).

Anyway, you found a way to get a correct answer with assume(a>0). The message you are seeing is only informational.
07-11-2017, 04:26 AM
Post: #3
 webmasterpdx Senior Member Posts: 541 Joined: Sep 2015
RE: hp prime simple integration doesn't work right...
The thing that bothers me (and others, as I've seen this in other places too), is that this does not occur on the TI-89, TI-NSPIRE, Wolfram alpha, or any of the other integration tools. This occurs on numerous integrals....the one I specified is one of the simplest e^-ax.....is about as simple an integral as is possible. It's a continuous function (no singularities). Why is the HP prime the only device that seems to be having this problem? If you work for HP, you should please look into this....Thx
Also, the message doesn't make sense.....saying taking the integral to infinity is difficult isn't an acceptable answer.....when every other tool can do it.....!!!
07-11-2017, 12:09 PM
Post: #4
 webmasterpdx Senior Member Posts: 541 Joined: Sep 2015
RE: hp prime simple integration doesn't work right...
I put in a new post to help others that may encounter these sorts of problems....here....