integrating with the HP Prime - Printable Version +- HP Forums ( https://www.hpmuseum.org/forum)+-- Forum: HP Calculators (and very old HP Computers) ( /forum-3.html)+--- Forum: HP Prime ( /forum-5.html)+--- Thread: integrating with the HP Prime ( /thread-7222.html) |

integrating with the HP Prime - Fanboy - 11-12-2016 08:35 AM
I'm trying to integrate 'e^(-B*x^2) from -inf to +inf' with the hp prime emulator. The calculator is not spitting out what I'm looking for which is sqrt(pi/B) and incorrectly gives infinity as the answer. However, it gives the correct answer (sqrt(pi)) when I just integrate 'e^(-x^2) from -inf to +inf' (without any letters). If I use a number instead of a letter, then it starts giving out the correct answer again. I'm completely new to the prime (currently have a 50G) so can anyone tell me how to get my answer in terms of the letter? I've posted a pic of the problem here: http://i1226.photobucket.com/albums/ee408/ForsakenSteel/HP%20Prime%20INT_zps09rhavgy.png RE: integrating with the HP Prime - parisse - 11-12-2016 10:28 AM
You should not use B as parameter, because B is always assigned on the Prime, by default to 0.0, and since exp(-B*x^2)=1 if B=0 this explains why the integral is infinity. Try with b instead. RE: integrating with the HP Prime - Fanboy - 11-12-2016 11:15 PM
How do we know which letters have a value attached to them like B? I noticed that the letters 'K' and 'A' also gave infinity as the answer. Also, if I use another letter like b or a, I get the answer as "undef". Its still not working. RE: integrating with the HP Prime - roadrunner - 11-13-2016 12:01 AM
You have to tell it that b isn't negative. Try typing: assume(b≥0) Then type: ∫(e^((-b)*x^2),x,-(∞),∞) You should get: √(π)/√(b) [attachment=4142] -road RE: integrating with the HP Prime - Fanboy - 11-13-2016 12:21 AM
Ok, that works. How do I remove that assumption? RE: integrating with the HP Prime - roadrunner - 11-13-2016 12:44 AM
(11-13-2016 12:21 AM)Fanboy Wrote: How do I remove that assumption? purge(b) |