using ode15s to solve differential equations

I am trying to solve differentials equations using ode15s. Have the following code:

function ode15s =(t,y);
%Define initial values of k1, k2,k3,S,P,E and C
k1=.005;
k2=.005;
k3=0.1;
S=100;
P=0;
E=10;
C=0;
y(1)=E;
y(2)=S;
y(3)=C;
y(4)=P;
y1=k2*y(3)+k3*y(3)-k1*y(1)*y(2);
y2=k2*y(3)+k1*y(1)*y(2);
y3=k1*y(1)*y(2)-(k2+k3)*y(3);
y4=k3*y(3);
y0=[0,0];
[t,y,k]=ode15(t,y);

I am getting the following errors: ode15s Error: File: ode15s.m Line: 1 Column: 12 Unexpected MATLAB operator.

>> ode15s Error: File: ode15s.m Line: 1 Column: 18 Unbalanced or unexpected parenthesis or bracket

I tried to rename the function (change it from ode15s and i get an error that says whatever i change it too it says that that name is recgoznied by matlab as ode15). I do not know how to fix this and/or what i may be missing in this code

Answer 1

[Azzi Abdelmalek]

You have a problem in the first line

function ode15s =(t,y)

Read the documentation about ode15s

doc ode15s

[KayLynn]

im am still not understanding what is wrong with my code....i have tried to change the format but it keeps saying there is an error

[Azzi Abdelmalek]

I don't think you read the documentation.

[KayLynn]

function X = question3(t,y)

y=[10 100 0 0]; %Define initial values of k1, k2,k3,S,P,E and C k1=.005; k2=.005; k3=0.1;

 %y(1)=E;
%y(2)=S;
 %y(3)=C;
 %y(4)=P;
x(1)=k2*y(3)+k3*y(3)-k1*y(1)*y(2);
x(2)=k2*y(3)+k1*y(1)*y(2);
x(3)=k1*y(1)*y(2)-(k2+k3)*y(3);
x(4)=k3*y(3);

[t,y,k]=ode15(t,y);

Attempted to change code accordingly and still running into problems. Not sure what I am missing