- 14 questions asked
- 3 answers
- 0 accepted answers
- reputation: 1
Undefined function 'int' for input arguments of type 'char'. keep getting error using matlab2015b
Latest activity Edited by Brian Hart
on 8 Dec 2018
- 0 questions asked
- 25 answers
- 11 accepted answers
- reputation: 50
eqa= 'diff(y(t),t)+y(t)-cos(t)';
neweq1a = laplace(eqa,t,s)
neweq1i = laplace(int('y(x)','x','0','t'),t,s)
neweq1 = neweq1a + neweq1i;
neweq2 = subs(neweq1,'y(0)',0)
lneweq2 = subs(neweq2,'laplace(y(t),t,s)',Ys)
soln = solve(lneweq2,Ys)
ysol = ilaplace(soln,s,t)
See Also
2 Answers
- 31 questions asked
- 42,610 answers
- 16,517 accepted answers
- reputation: 85,656
Answer by Walter Roberson
on 8 Dec 2018
- 31 questions asked
- 42,610 answers
- 16,517 accepted answers
- reputation: 85,656
You probably do not have the Symbolic Toolbox installed.
Note that that code would not work in current versions of MATLAB (R2018a and later.) It should be modernized even for your version.
syms s x y(t) Ys
dy = diff(y(t), t);
eqa= dy + y(t) - cos(t);
neweq1a = laplace(eqa, t, s)
inty = int(y(x), x, 0, t);
neweq1i = laplace(inty, t, s)
neweq1 = neweq1a + neweq1i;
neweq2 = subs(neweq1, y(0), 0)
lapy = laplace(y(t), t, s)
lneweq2 = subs(neweq2, lapy, Ys)
soln = solve(lneweq2, Ys)
ysol = ilaplace(soln, s, t)
This still requires the Symbolic Toolbox, but has been rewritten to avoid needing to process character strings.
0 Comments
Sign in to comment.
- 0 questions asked
- 25 answers
- 11 accepted answers
- reputation: 50
In the first line you define an eqution as a text string (in quotes). Then in the second line you pass that text string into the laplace function, which expects a symbolic function. See the help pages for laplace and syms.
I think your specified error comes from the third line. The function int also wants a symbolic function, not text (which is of type 'char').
0 Comments
Sign in to comment.
See Also
Discover what MATLAB® can do for your career.
Opportunities for recent engineering grads.
Apply Today
0 Comments
Sign in to comment.