Why did this error message appear?
162 views (last 30 days)
Show older comments
Unable to perform assignment because value of type 'sym' is not convertible to 'double'.
line10.Unable to convert expression containing symbolic variables into double array. Apply 'subs' function first to
substitute values for variables.
- m=600:1200;
- r=ones(20,601);t=ones(20,601);
- n0=1;
- n1=1.75;d1=125;
- n2=2.5;d2=87.5;
- n3=1.45;
- k=2*pi./m;
- e1=n1*d1*k;e2=n2*d2*k;
- x1= sym('x1',[1,601]);
- r(1,:)=(n0+n1)/(2*n1)+(n1-n0)/(2*n1)*x1;
- t(1,:)=(n1-n0)/(2*n1)+(n1+n0)/(2*n1)*x1;
- for i=2:20
- if rem(i,2)==0
- t(i,:)=(n1+n2)/(2*n2)*t(i-1)*exp(2*e1*1i)+(n1-n2)/(2*n2)*r(i-1)*exp(-2*e1*1i);
- r(i,:)=(-n1+n2)/(2*n2)*t(i-1)*exp(2*e1*1i)+(n2+n1)/(2*n2)*r(i-1)*exp(-2*e1*1i);
- else
- t(i,:)=(n1+n2)/(2*n1)*t(i-1)*exp(2*e2*1i)+(n2-n1)/(2*n1)*r(i-1)*exp(-2*e2*1i);
- r(i,:)=(-n2+n1)/(2*n1)*t(i-1)*exp(2*e2*1i)+(n2+n1)/(2*n1)*r(i-1)*exp(-2*e2*1i);
- end
- end
- solve(r(20,:),x);
- T=t(20,:).*conj(t(20,:))*n3;
- plot(m,T);
0 Comments
Answers (1)
Steven Lord
on 14 Nov 2021
Since r is a double array, anything that you want to assign into it must be a double array or convertible into a double array.
In this example:
r = 1:10
syms x y
z = x.^2+y.^2
what is the double precision value of z? Without having values for x and y we cannot convert z into a double array, and so trying to store z inside r won't work.
r(1) = z
You could make r a symbolic array from the start, or you could substitute values for x and y into z (thus making z a plain number.)
rsym = sym(1:10)
See Also
Products
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!