Solving ODE in MATLAB help needed

Question: Solve numerically up to t=1
a) x= 20, values for y and z
b) x= 9, values for y and z

Equations:

{dVx/dt= -(k/m)Vx-cVy;}   
[dVy/dt= -(k/m)Vy-cVx:]  
[dVz/dt= -(k/m)Vz-g:]

I tried the first equation:

function x = test_dVxdt (t,x)
global k m c Vx Vy

x = -(k/m)Vx - cVy;

return

In the command window

   k= 0.17;
  >> m= 0.43;
  >> c= 0.24

c =

      0.2400

>> Vx= 26.76;
>> Vy= -2.813;
>> tspan= [0:0.1:1];
>> 
>> x= 20;
>> [t, x] = ode45(@test_dVxdt, tspan, x)

But I am getting a lot of errors,

Error using feval
Error: File: test_dVxdt.m Line: 4 Column: 11
Unexpected MATLAB expression.

Error in odearguments (line 88)
f0 = feval(ode,t0,y0,args{:});   % ODE15I sets args{1} to yp0.

Error in ode45 (line 114)
[neq, tspan, ntspan, next, t0, tfinal, tdir, y0, f0, odeArgs, odeFcn, ...

Am I going about the question correctly? Any help would be appreciated.

Answer 1

[Sachin Ganjare]

Rfer below link:

http://stackoverflow.com/questions/12720549/matlab-ode45-basic-setup

Hope you will find the answer!!!

Answer 2

[Walter Roberson]

-(k/m)Vx does not indicate multiplication in MATLAB. -(k/m) .* Vx

Likewise for other multiplication operations in your code.