Finding capable function in an equation with Mathematica or Matlab [closed]

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I want to find a function f(xi) that suffices the following equation:

(vi-xi)f(xi)'=f(xi)

when xi = k*vi, where vi is a constant and xi is the variable.

Anyone know howto describe this problem in mathematica or matlab? Great Thanks!

Answer 1

Mathematica

eq = (vi - xi) D[f[xi], xi] == f[xi];
DSolve[eq, f[xi], xi]

(* {{f[xi] -> C[1]/(vi - xi)}} *)

Matlab

syms vi xi f(xi)
dsolve( (vi -xi)*diff(f)==f)

ans =

C2/(vi - xi)

Maple

restart;
dsolve((vi - xi)*diff(f(xi),xi)=f(xi),f(xi));
(*  f(xi) = _C1/(vi-xi) *)