Error using Contour: input arguments must be numeric or objects which can be converted to a double

Hi, I have the given code where I try to plot levels curves of the givenfunction
syms r x y k z
[ph,r] = meshgrid((0:5:360)*pi/180,0:.5:10);
[X,Y] = pol2cart(ph,r);
Z = X+i*Y;
J = besselj(k,l.*r);
J2 = besselj(k,m.*r);
Y = bessely(k,l.*r);
Y2 = bessely(k,m.*r);
H = besselh(k,r);
F1 = symsum((J).*exp(1i*k*ph),k,-5,5);
F2 = symsum((J2+Y2).*exp(1i.*k.*ph),k,-5,5);
F3 = symsum(H.*exp(1i.*k.*ph),k,-5,5);
pwu = nan(size(F1), 'like', F1);
mask = 0 <= r & r < 0.5;
pwu(mask) = F1(mask);
mask = 0.5 <= r & r < 1;
pwu(mask) = F2(mask);
mask = r >= 1;
pwu(mask) = F3(mask);
U = subs(pwu, {l, m}, {1.5, 3});hold on
contour(X,Y,imag(double(U)),30)
axis equal
xlabel('r','FontSize',14);
ylabel('phi','FontSize',14);
But I get an error for the 4th last line. How can this be made in a way it is converted to a double?
Thanks!

1 个评论

I'm not able to run this script because the variables l, m, n, etc are not defined. Could you update the attached code so that your error can be reproduced?

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 采纳的回答

Yes, here it is, working script
syms r x y k z l m
[ph,r] = meshgrid((0:5:360)*pi/180,0:.5:10);
[x,y] = pol2cart(ph,r);
Z = x+1i*y;
J = 0.9426656*besselj(k,l.*r);
J2 = 0.640840882*besselj(k,m.*r);
Y = bessely(k,l.*r);
Y2 = 0.4361500838*bessely(k,m.*r);
H = 1.1159118143*besselh(k,r);
F1 = symsum((J).*exp(1i*k*ph),k,-5,5);
F2 = symsum((J2+Y2).*exp(1i.*k.*ph),k,-5,5);
F3 = symsum(H.*exp(1i.*k.*ph),k,-5,5);
pwu = nan(size(F1), 'like', F1);
mask = 0 <= r & r < 0.5;
pwu(mask) = F1(mask);
mask = 0.5 <= r & r < 1;
pwu(mask) = F2(mask);
mask = r >= 1;
pwu(mask) = F3(mask);
U = subs(pwu, {l, m}, {1.5, 3});hold on
w=double(U)
contour(x, y, angle(double(U)), 30);
axis equal
xlabel('r','FontSize',14);
ylabel('phi','FontSize',14);

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