assumptions in integrals' computation in programming mode
10-29-2022, 11:07 AM
Post: #1
 robmio Member Posts: 172 Joined: Jan 2020
assumptions in integrals' computation in programming mode
Good morning, if I want to calculate the following integral:

int((t-x)^(-1/2)*ln(x),x,0,t)

it is necessary to make the following assumptions:

My question is the following: how can I assign an assumption to a variable in #cas ... #end programming mode?

See attachments

Thanks a lot, Roberto (robmio)

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10-29-2022, 12:43 PM
Post: #2
 Ioncubekh Junior Member Posts: 42 Joined: Oct 2022
RE: assumptions in integrals' computation in programming mode
Code:
assume(t>0 AND t>x)

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10-29-2022, 01:38 PM
Post: #3
 robmio Member Posts: 172 Joined: Jan 2020
RE: assumptions in integrals' computation in programming mode
(10-29-2022 12:43 PM)Ioncubekh Wrote:
Code:
assume(t>0 AND t>x)

Thank you for the answer, but my question is another: in which area of a program do I put the instruction "assume"? For example, in this "#cas ... #end" program:

#cas
cavolo():=
BEGIN
LOCAL fnz, Fnz;
fnz:=(x)->(t-x)^(-1/2)*LN(x);

Fnz:=(t)->int(fnz(x),x,0,t);

RETURN Fnz(t);

END;
#end

in which zone do I put "assume(...)"?
Putting the "assume()" statement between the "fnz" statement and the "Fnz" statement, I get nothing.

Thanks a lot, robmio
10-29-2022, 02:07 PM
Post: #4
 robmio Member Posts: 172 Joined: Jan 2020
RE: assumptions in integrals' computation in programming mode
(10-29-2022 12:43 PM)Ioncubekh Wrote:
Code:
assume(t>0 AND t>x)

I solved the problem:

#cas
...
Fnz:=(t)->int((t-x)^(-1/2)*ln(x),x,0,assume(t>0 AND t>x));
...

#end

It works!
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