I am trying to execute the code written below and getting the error given below, help me to fix this error?
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The following error occurred converting from sym to double: Error using mupadmex Error in MuPAD command: DOUBLE cannot convert the input expression into a double array.
If the input expression contains a symbolic variable, use the VPA function instead.
Error in ExampleLoop (line 13) h(i,j) = 10*(((t(i,j)-.1)/.4)^-0.5-1)^.5;
code: clc; clear all; close all;
t = zeros(100,48); t(1,:) = .5;
t(:,1) = 0;
d = zeros(100,48);
k = zeros(100,48);
h = zeros(100,48);
syms t(i,j);
h(i,j) = 10*(((t(i,j)-.1)/.4)^-0.5-1)^.5;
k(i,j) = 10^-8*(t(i,j)-.1)/(.4)*(1-(1-((t(i,j)-.1)/0.4)^2)^.5)^2;
dh_dt(i,j) = diff(h(i,j));
dk_dt(i,j) = diff(k(i,j));
c(i,j) = 1/(dh_dt(i,j));
d(i,j) = k(i,j)/c(i,j);
dd_dt(i,j) = diff(c(i,j));
for i=2:99;
for j=1:47;
a = (1-.5*d(i,j)-.5*d(i+1,j));
b = .5*d(i,j);
c = .5*d(i+1,j);
t(i,j+1) = a*t(i,j)+b*t(i-1,j)+c*t(i+1,j)+.5*(k(i+1,j)-k(i-1,j));
end
end
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Accepted Answer
Star Strider
on 30 Apr 2014
There are a few things wrong that I can see:
Do not use the ‘syms’ statement. You don’t need it. Use nested for loops for ‘i’ and ‘j’ instead.
In this and other statements like it:
dh_dt(i,j) = diff(h(i,j));
you are taking the difference of a single scalar element. That is not possible. (This would not have worked as a symbolic either, because your h matrix was not created as a function of a symbolic variable.)
What do you want to do in your code?
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