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How can I fix the code?

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Anh Thu
Anh Thu on 30 Jul 2018
Closed: MATLAB Answer Bot on 20 Aug 2021
I'm trying to calculate the sum of f(z1^i,z2^j) for i,i=1:2m and x1,x2 are chosen before (are nodes). Here is my code in Matlab
% code
k=5;r0=0.5; M=1000; m=100; h=r0/m;
ui=@(x,y) exp(5i*y);
a=@(x,y)( 0.01*exp(1-(0.25/(0.25-x.^2-y.^2))).*(x.^2+y.^2 < 0.25)+0.*( x.^2+y.^2 >=0.25));
% a=0.01*exp(1-(0.25/(0.25-x^2-y^2) if x^2+y^2 < 0.25 and a=0 otherwise.
f=@(x1,x2,y1,y2) -1i.*k.^2./4.*besselh(0,sqrt((x1-y1).^2+(x2-y2).^2)).*a(y1,y2).*ui(y1,y2);
s=0;
for p=1:2*m
x1=-r0+p*h;
for q=1:2*m
x2=-r0+q*h;
for i=1:2*m
z1=-r0+(i/2)*h;
for j=1:2*m
z2=-r0+(j/2)*h;
s=s+f(x1,x2,z1,z2);
disp(s);
disp(f(x1,x2,z1,z2));
end
end
end
Matlab can't show the results of 's' but can show the results of 'f(x1,x2,z1,z2)'. How can I fix the code?
  2 Comments
Walter Roberson
Walter Roberson on 30 Jul 2018
What happens if you try to display s? Is there an error message?
Anh Thu
Anh Thu on 31 Jul 2018
it display "NaN+NaNi"

Answers (1)

OCDER
OCDER on 30 Jul 2018
For some reason, you're getting a NaN + NaNi, a complex imaginary NaN. Try to skip these, otherwise s will just become NaN + NaN*i.
% code
k=5;r0=0.5; M=1000; m=100; h=r0/m;
ui=@(x,y) exp(5i*y);
a=@(x,y)( 0.01*exp(1-(0.25/(0.25-x.^2-y.^2))).*(x.^2+y.^2 < 0.25)+0.*( x.^2+y.^2 >=0.25));
% a=0.01*exp(1-(0.25/(0.25-x^2-y^2) if x^2+y^2 < 0.25 and a=0 otherwise.
f=@(x1,x2,y1,y2) -1i.*k.^2./4.*besselh(0,sqrt((x1-y1).^2+(x2-y2).^2)).*a(y1,y2).*ui(y1,y2);
s=0;
for p=1:2*m
x1=-r0+p*h;
for q=1:2*m
x2=-r0+q*h;
for i=1:2*m
z1=-r0+(i/2)*h;
for j=1:2*m
z2=-r0+(j/2)*h;
Out = f(x1,x2,z1,z2);
if ~isreal(Out); continue; end
s=s+Out;
disp(s);
disp(Out);
end
end
end
end

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