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Question: effect of evala on expression when using integrate command

Question:effect of evala on expression when using integrate command

nm 9899 Maple 2023
integration int evala timelimit
June 02 2023
1

Could someone help me understand why Maple's int hangs when using int on an integrand if evala is not first applied to the integrand?

When I mean hangs, I mean really hangs. I have timelimit and maple server.exe runs at high CPU for hrs. When adding evala(), it completes instantly and returns unevaluated integral (which is just fine as I did not expect this to be evaluated) but it does not hang which is the main point.

Is this considered normal behaviour or a bug?  Should then one always add evala() on the integrand before using int?  As I get many hangs on int (even when using timelimit). I am not familiar with evala command as I have never had to use it before, but by chance I tried it and noticed this.

V 2023 on windows 10. Worksheet attached.


 

186932

> 

restart;

186932

> 

expr:=-1/3*2^(2/3)/((a^2*p+2*a*p^2+p^3+4)/p)^(1/2)*((-1/2*a^2*p-1/2*p^2*a+1/2*p*((a^2*p+2*a*p^2+p^3+4)/p)^(1/2)*a-3)*(-p^2*(-((a^2*p+2*a*p^2+p^3+4)/p)^(1/2)+a+p))^(2/3)+2^(2/3)*p*(-(a+3/2*p)*p*((a^2*p+2*a*p^2+p^3+4)/p)^(1/2)+a^2*p+5/2*p^2*a+3/2*p^3+3))/(-((a^2*p+2*a*p^2+p^3+4)/p)^(1/2)+a+p)/(-1/2*2^(2/3)*(-p^2*(-((a^2*p+2*a*p^2+p^3+4)/p)^(1/2)+a+p))^(2/3)+p*(p*(-p^2*(-((a^2*p+2*a*p^2+p^3+4)/p)^(1/2)+a+p))^(1/3)+2^(1/3)))/p^2:
try
    anti := timelimit(30,int(evala(expr),p));
catch:
    print("timed out OK");
end try:
print("done");

"done"

> 

restart;
> 

expr:=-1/3*2^(2/3)/((a^2*p+2*a*p^2+p^3+4)/p)^(1/2)*((-1/2*a^2*p-1/2*p^2*a+1/2*p*((a^2*p+2*a*p^2+p^3+4)/p)^(1/2)*a-3)*(-p^2*(-((a^2*p+2*a*p^2+p^3+4)/p)^(1/2)+a+p))^(2/3)+2^(2/3)*p*(-(a+3/2*p)*p*((a^2*p+2*a*p^2+p^3+4)/p)^(1/2)+a^2*p+5/2*p^2*a+3/2*p^3+3))/(-((a^2*p+2*a*p^2+p^3+4)/p)^(1/2)+a+p)/(-1/2*2^(2/3)*(-p^2*(-((a^2*p+2*a*p^2+p^3+4)/p)^(1/2)+a+p))^(2/3)+p*(p*(-p^2*(-((a^2*p+2*a*p^2+p^3+4)/p)^(1/2)+a+p))^(1/3)+2^(1/3)))/p^2:
try
    anti := timelimit(30,int(expr,p));
catch:
    print("timed out");
end try;
print("done");


The second case above just hangs. Make sure to save all your work. I found I have to terminate all of Maple sometimes as killing server.exe seems to make the frontend hangs and not respond, ending up losing work in other worksheets which I did not save.

Download int_hangs_june_2_2023.mw
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