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Error in symengine for symbolic integration

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vahid s
vahid s 2021-8-18
评论： vahid s 2021-8-20
I want to calculate a symbolic integration like below:
syms z
hc=2.5e-9;
hp=1e-9;
e31=-2.2;
z1=z-hc-(hp/2);
z2=z+hc+(hp/2);
B31_1=double(int(e31*(pi/hp)*(sin(pi*z2/hp))*(z^1),'z',-hc-hp,-hc)+int(e31*(pi/hp)*(sin(pi*z1/hp))*(z^1),'z',hc,hc+hp));
But I get this error:
Error using symengine
Out of memory.
Error in sym/int (line 167)
rSym = mupadmex('symobj::intdef',f.s,x.s,a.s,b.s,options);
Note: For z^0 there is no error, but when z has power, this error appears.
What is solution for this? Thanks in advance.
  4 个评论
显示 2更早的评论
Walter Roberson
Walter Roberson 2021-8-19
编辑：Walter Roberson 2021-8-19
On my system, in R2020a, it does not even use as much as 1 gigabyte between MATLAB itself and the MuPAD process to do the integration. No hint of a problem at all. MacOS.
vahid s
vahid s 2021-8-19
I have 4 GB RAM, and also matlab doesn't freeze to use memory. It shows error immediately. Since I prefer using "syms" instead of "@fun", I reported this problem.
Thanks for your answer.

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采纳的回答

Wan Ji
Wan Ji 2021-8-19
This is a bug in matlab. A good way to avoid this bug is just to predefine symbols rather than use constants in the symbolic process. When symbolic formula is derived, use subs and eval function to obtain the final results.
syms z hc hp e31
z1=z-hc-(hp/2);
z2=z+hc+(hp/2);
p = e31*(pi/hp)*(sin(pi*z2/hp))*z^1;
q = e31*(pi/hp)*(sin(pi*z1/hp))*z^1;
B31_1 = int(p,z,-hc-hp,-hc)+int(q,z,hc,hc+hp)
B31_1_val = eval(subs(B31_1,[hc,hp,e31],[2.5e-9, 1e-9, -2.2]))
The result in this
B31_1 =
(4*e31*hp)/pi
B31_1_val =
-2.801126998417358e-09
Since you observed this bug, I suggest you report it to MATHWORKS. You will be really appreciated. ovo
  1 个评论
vahid s
vahid s 2021-8-20
Thank you so much for solution.
I think this bug is solved in newest version R2021a, so maybe there is no point for reporting this bug since it is solved.

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