I am tyring to implement a code with a loop. But my output variable is a NaN, but it must be a number in output. I am not sure what's wrong. Can anyone help?

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ravi poudel
ravi poudel 2022-7-6
评论： ravi poudel 2022-7-6
a = (D1/2)-(D2_cor/2) % the major axis the ellipse - ??
b = a*0.75
ellipse = [a,b]
ellipse_length = 0 % inlitialize integral
integral_start = 0 % Integrate from ...
ns = 18 % number of streamlines
np = 40 % number of points per streamlines
% Integrate to end of ellipse , minus a small part to avoid infinite integral. ..??
integral_end = ellipse(1) - 0.0001
integral_step = 100000 % integral step
dx = (integral_end - integral_start)/integral_step % initializing dx
%now we make integral start to find the length of the ellipse along ring
for x = integral_start : dx : integral_end
dydx = (1/2)*ellipse(2)*(1-(x/ellipse(1)^2)^(-0.5))*(-(2*x/(ellipse(1)^2)));
ellipse_length = ellipse_length + sqrt(1+(dydx)^2)*dx;
end
% here the output in the variable "ellipse_length" is a NaN. I don't know whats wrong. Can anyone suggest me what is wrong here?

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采纳的回答

Sam Chak
Sam Chak 2022-7-6
@ravi poudel
Please check your code if singularity occurs in this line:
dydx = (1/2)*ellipse(2)*(1-(x/ellipse(1)^2)^(-0.5))*(-(2*x/(ellipse(1)^2)));

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