How to fix "Error using indexing" while calculating differential equations?

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Iita
Iita el 29 de Jun. de 2024
Editada: John D'Errico el 30 de Jun. de 2024
syms y(t)
ode = diff(y,t) == t*y
ode(t) = 
ySol(t) = dsolve(ode)
ySol(t) = 
I copied this example straight from the MatLAB "Solve differential equations" > "First-Order Linear ODE" -example and hoped to modify it to solve my own equation, but it gives me an error message of "Error using indexing: Invalid argument at position 2. Symbolic function expected 1 input arguments but received 2.". I have no clue how to fix it, so help would be kindly appreciated.
  3 comentarios
Iita
Iita el 29 de Jun. de 2024
Ah, I've got the R2023a version. I imagine an update would fix things quite efficiently :,D
Torsten
Torsten el 29 de Jun. de 2024
Editada: Torsten el 29 de Jun. de 2024
I don't see any changes made in "dsolve" from R2023a to R2024a, but you can try.
Do you get the same error with this code ? Or does the error happen later on in your code when you try to manipulate ySol ?
syms y(t)
ode = diff(y,t) == t*y;
ySol = dsolve(ode)
ySol = 

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John D'Errico
John D'Errico el 30 de Jun. de 2024
Editada: John D'Errico el 30 de Jun. de 2024
The code you show will work perfectly in MATLAB, in literally any recent release of MATLAB. R2023 is entirely recent.
However, it is very possible that you have defined a variable named diff in your workspace. For example, let me do this:
syms y(t)
diff(t) = y(t)
diff(t) = 
ode = diff(y,t) == t*y
Error using indexing (line 249)
Invalid argument at position 2. Symbolic function expected 1 input arguments but received 2.
Do you see that I have gotten exactly the same error you were given?
Do this at the command line:
whos diff -all
And then delete the variable named diff.

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