Numerical integration
02-01-2018, 02:37 AM
Post: #1
 scublue Junior Member Posts: 3 Joined: Mar 2017
Numerical integration
HP prime can not give the right answer such as int(sin(1/x)/x^(3/2),x,1,+infinity), how cold i calculate such kind of numerical integration. Thank you very much.
02-01-2018, 04:03 AM
Post: #2
 Joe Horn Senior Member Posts: 1,411 Joined: Dec 2013
RE: Numerical integration
In CAS, use a lowercase "x" for the variable, and use "1." (instead of "1") for the lower limit, and you'll get 0.620536603447 which is the correctly rounded answer. Including a decimal point forces a numeric result instead of a symbolic result.

Or you can use "1" as the lower limit, press Enter, and then press the [a b/c] key to approximate it.

Or change the "Exact" mode in CAS Settings to OFF.

X<> c
-Joe-
02-01-2018, 04:08 AM
Post: #3
 Carlos295pz Member Posts: 279 Joined: Sep 2015
RE: Numerical integration
Xcas also does not find an answer, they must have an extraterrestrial mathematical reason xD

Viga C | TD | FB
02-01-2018, 07:00 AM
Post: #4
 scublue Junior Member Posts: 3 Joined: Mar 2017
RE: Numerical integration
However, i got the answer like this 0.6417....

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02-01-2018, 07:48 AM
Post: #5
 salvomic Senior Member Posts: 1,364 Joined: Jan 2015
RE: Numerical integration
(02-01-2018 04:08 AM)Carlos295pz Wrote:  Xcas also does not find an answer, they must have an extraterrestrial mathematical reason xD

in CAS there is an extraterrestrial mathematical reason also for simply ∫SIN(1/x) or ∫COS(1/x) :-)

∫aL√0mic (IT9CLU), HP Prime 50g 41CX 71b 42s 12C 15C - DM42 WP34s :: Prime Soft. Lib
02-02-2018, 05:23 PM
Post: #6
 Tim Wessman Senior Member Posts: 2,069 Joined: Dec 2013
RE: Numerical integration
As Joe said, do it in the CAS screen and you get the desired result. The problem with doing it in the home is you hit numerical limitations with 12 digits and also approximations.

TW

Although I work for the HP calculator group, the views and opinions I post here are my own.
02-04-2018, 05:02 AM
Post: #7
 Joe Horn Senior Member Posts: 1,411 Joined: Dec 2013
RE: Numerical integration
(02-01-2018 07:00 AM)scublue Wrote:  However, i got the answer like this 0.6417....

You have to be more careful with where you put parentheses. Your original posting's expression is different from your recently posted expression. You can see them both here:

X<> c
-Joe-
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