i=dsolve('​Dy=-8*y+40​*sin(8*t)'​,'y(0)=5') Warning: Support for character vector or string inputs will be removed in a future release. Instead, use syms to declare variables and replace inputs such as dsolve('Dy = -3*y') with syms y(t); dsolve(diff(y,

i=dsolve('Dy=-8*y+40*sin(8*t)','y(0)=5')

Warning: Support for character vector or string inputs will be

removed in a future release. Instead, use syms to declare

variables and replace inputs such as dsolve('Dy = -3*y') with syms

y(t); dsolve(diff(y,t) == -3*y). > In dsolve (line 126)

[Noah Prisament]

Hi Juan, this question would be better posted in MATLAB Answers. But to resolve this warning, you can use the dsolve syntax described in the warning and explained in this documentation: https://www.mathworks.com/help/symbolic/dsolve.html which uses symbolic equations instead of an equation string.

[Walter Roberson]

syms y(t)
i = dsolve(diff(y) == -8*y + 40*sin(8*t), y(0) == 5)

This leads to the result

i =

(15*exp(-8*t))/2 - (5*2^(1/2)*cos(8*t + pi/4))/2