Integral crash

01062023, 04:18 PM
(This post was last modified: 01062023 05:38 PM by Albert Chan.)
Post: #1




Integral crash
∫(sec(x), x = 0 .. pi/6) = gd^{1}(pi/6) = asinh(tan(pi/6)) ≈ 0.549306
However, when I try to "fold" it, XCas crashes. XCas> 2*cos(pi/12)* ∫(cos(pi/12x) / (cos(x)*cos(pi/6x)), x = 0 .. pi/12) Tested on XCas 1.9.022 (win32) → CRASH Interestingly, XCas 1.5.063 (win32) (old version), does not have problem with this. I wonder if latest HP Prime, with code based from XCas, will fail too ... 

01062023, 05:11 PM
Post: #2




RE: Integral crash
I tried the original formula as well as the "folded" formula with the physical calculator (G1 and G2, both version 2.1.14603 from Dec. 2021) and all worked quite well. If you put a decimal point after each number you immediately get the result 0.549306, if you do not, you get a strange expression but if you evaluate it you get the same result.
So there seems to be no problem with the physical calculators and the software version from Dec. 2021. 

01062023, 06:31 PM
Post: #3




RE: Integral crash
Thanks rawi,
That narrowed down the bug from Dec 2021 to Sep 2022 (latest XCas 1.9.022) while we are at it, there is an annoying bug, which old XCas 1.5.0 does not have. XCas> plot([sin(x), cos(x)], x = 0 .. 2*pi, color=[blue, red]) XCas> plot([sin(x), cos(x)], x = 0 .. 2*pi, legend=["sin", "cos"]) 1st plot, both curves are drawn in blue 2nd plot, both curves have legend ["sin" To make the curves match color/legend, we have to put both in. XCas> plot([sin(x), cos(x)], x = 0 .. 2*pi, color=[blue,red], legend=["sin", "cos"]) 

01062023, 06:53 PM
Post: #4




RE: Integral crash
1.9.031 is the latest version, and the integral is correct there.
I'll have a look at plot ASAP. I made changes so that plot can guess a parametric plot as argument, this might be the reason. If you run plotfunc instead that should work. 

01062023, 08:17 PM
Post: #5




RE: Integral crash
Hi, parisse
I downloaded XCas 1.9.031 (mingw), it work! Thanks! XCas 32bits version is still 1.9.022 though (when will it catch up 64bits versions?) Bonus, result is a lot less messy than expected XCas> 2*cos(pi/12)* ∫(cos(pi/12x) / (cos(x)*cos(pi/6x)), x = 0 .. pi/12) \(\displaystyle  \frac{\left(\sqrt{2}+\sqrt{6}\right) \left(\sqrt{2} \ln \left(\frac{\sqrt{2}}{2}\right)+\sqrt{2} \ln \left(\frac{\sqrt{6}}{2}\right)+\sqrt{6} \ln \left(\frac{\sqrt{2}}{2}\right)\sqrt{6} \ln \left(\frac{\sqrt{6}}{2}\right)\right)} {4}\) XCas> simplify(ans()) → (ln(2)+ln(6))/2 XCas> simplify(ans()) → ln(3)/2 Also, plotfunc for plot fixed the color/legend issues. What is the difference between the two? 

01062023, 10:18 PM
Post: #6




RE: Integral crash
Latest XCas version 1.9.031, changed string default color.
It went from "Hello, world" to "Hello, world" I tried cfg color menu, but there does not seems to a way to switch it back. 

01082023, 07:45 PM
Post: #7




RE: Integral crash
XCas 1.9.0.31 (mingw), if I run anything, say 1 Enter
CtrlQ (to quit), Enter, escape, Enter, escape I get this repeated message, and the system hang. *** bug in PARI/GP (Segmentation Fault), please report *** 

01082023, 10:10 PM
Post: #8




RE: Integral crash
Indeed, this will be fixed in 1.9.037.
(BTW, you should probably create an account on Xcas forum to report that kind of bugs) 

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