Error in symengine for symbolic integration
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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 Comments
Walter Roberson
on 19 Aug 2021
Edited: Walter Roberson
on 19 Aug 2021
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.
Accepted Answer
Wan Ji
on 19 Aug 2021
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
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