Numerical integration

[scublue]

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.

[Joe Horn]

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.

[Carlos295pz]

Xcas also does not find an answer, they must have an extraterrestrial mathematical reason xD

[scublue]

However, i got the answer like this 0.6417....

[salvomic]

(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) :-)

[Tim Wessman]

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.

[Joe Horn]

(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: