inline.inline at 47

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Aldin
Aldin on 4 Mar 2012
Hello people,
Can someone explain what's kind of error is this:
inline.inline at 47 Input must be a string.
P.S. I use diff function in my code.
Thanks.

Accepted Answer

Walter Roberson
Walter Roberson on 4 Mar 2012
syms x
fun = sym( get(handles.edit4,'String') );
f = matlabFunction(fun, x);
dfun = diff( fun, x );
df = matlabFunction(dfun, x);

More Answers (1)

Wayne King
Wayne King on 4 Mar 2012
The kind of error you are reporting comes from trying to input a non-string input in inline()
For example:
t = 10;
g = inline(t^2);
Are you trying to do symbolic differentiation?
  4 Comments
Walter Roberson
Walter Roberson on 4 Mar 2012
Your "y" is a string. A string is an array of characters. diff(y) applied to an array of anything other than symbolic expressions gives [y(2)-y(1), y(3)-y(2), y(4)-y(3)] and so on.
*Only* symbolic expressions can be differentiated.
Wayne King
Wayne King on 4 Mar 2012
Hi, No, because diff(y) here is going to return a double-precision vector, which results in the error I showed you above.

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