Please help with using ode45

Please assist me with resolving the errors I'm getting.

Heres my functions:

function output=funct(A,B,C,D,E,F,tmin,tmax)

[t,y]=ode45('func',[tmin tmax],[0 0 0]);

plot(t,y(:,1))

end

This is the function im attempting to cal

function ydot=func(t,y)

ydot(1)=y(2);

ydot(2)=y(3);

ydot(3)=((F*exp(-0.1*t)*cos(t))+(B*y(3))-(C*t*y(2))+(E*y(1)))/A;

ydot=ydot';

end

Here are my erros

Cannot find an exact (case-sensitive) match for 'F'

The closest match is: f in C:\Users\Christopher\Documents\MATLAB\f.m

Error in func (line 4)

ydot(3)=((F*exp(-0.1*t)*cos(t))+(B*y(3))-(C*t*y(2))+(E*y(1)))/A;

Error in odearguments (line 90)

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

Error in ode45 (line 115)

      odearguments(FcnHandlesUsed, solver_name, ode, tspan, y0, options, varargin);

Error in funct (line 2)

[t,y]=ode45('func',[tmin tmax],[0 0 0]);

[Star Strider]

Related: ode45 for third order differential (link)

Answer 1

[Walter Roberson]

You need to pass some of the variables into your fun.

http://www.mathworks.com/help/matlab/math/parameterizing-functions.html

[Christopher Carey]

Hey trying to attempt this but still getting errors

New Code:

function output=funct(A,B,C,D,E,F,tmin,tmax)

[t,y]=ode45('func',[tmin tmax],[0 0 0]);

function ydot=func(t,y)

ydot(1)=y(2);

ydot(2)=y(3);

ydot(3)=((F*exp(-0.1*t)*cos(t))+(B*y(3))-(C*t*y(2))+(E*y(1)))/A;

ydot=ydot';

end

plot(t,y(:,1))

end

Error:

>> func(1, 5, 7, 9, 11, 13, 0, 20)

Not enough input arguments.

Error in func (line 2)

[t,y]=ode45('func',[tmin tmax],[0 0 0]);

Error in odearguments (line 90)

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

Error in ode45 (line 115)
    odearguments(FcnHandlesUsed, solver_name, ode, tspan, y0, options, varargin);

Error in func (line 2)

[t,y]=ode45('func',[tmin tmax],[0 0 0]);

[Walter Roberson]

You need to change

[t,y]=ode45('func',[tmin tmax],[0 0 0]);

to

[t,y] = ode45(@func,[tmin tmax],[0 0 0]);

You posted,

>> func(1, 5, 7, 9, 11, 13, 0, 20)

Not enough input arguments.

Error in func (line 2)

[t,y]=ode45('func',[tmin tmax],[0 0 0]);

However, that code does not occur on line 2 of func. Line 2 of func is the empty line between the 'function' header and the line

ydot(1)=y(2);

That code instead appears at line 2 of funct . With your having defined func as a nested function, there is no way you could have called func directly from the command line.

These facts suggest that you placed funct (with a t) in a file named func.m . Don't do that. Name the file funct.m