undefined function 'f'

tmesh = linspace(0,pi/2,5);
solinit = bvpinit(tmesh, @f);
sol = bvp4c(@odefun, @bcfun, solinit);
 plot(sol.x, sol.y, '-o');
 

FUNCTION

function dzdt = odefun(t,z)
dzdt = zeros(2,1);  
dzdt = [z(2)+z(1)];    
end
% boundary conditions
function res = bcfun(za, zb)
    res = [za(1) zb(pi/2)-2]
end
% Initial guess
function g = f(t)
 g = [sin(t) cos(t)];
end

error unrecognized function or variable 'f'

[KSSV]

Did you save the function in the working folder?

[Walter Roberson]

If you stored those three functions together in one file, and had the script in another file, then the script would only be able to see the first function inside the file of functions. Only the first function in a file of functions is visible to the outside normally; the rest are private implementations only for use by that function (typically)

[Titas Chattopadhyay]

So, I have to make 3 function files for func ,bcs and ics. Right?

Answer 1

[Ameer Hamza]

Either write all the functions in one file like this. (Also note that I have made few changes in your code.)

tmesh = linspace(0,pi/2,5);
solinit = bvpinit(tmesh, @f);
sol = bvp4c(@odefun, @bcfun, solinit);
plot(sol.x, sol.y, '-o');

function dzdt = odefun(t,z)
    dzdt = zeros(2,1);  
    dzdt = [z(2); z(1)]; % <----- This should be a 2x1 vector
end

% boundary conditions
function res = bcfun(za, zb)
    res = [za(1); zb(2)-2]; % <---- boundary conditions are written like this, zb(pi/2) is invalid
end

% Initial guess
function g = f(t)
    g = [sin(t) cos(t)];
end

Or create 4 files like this.

main_script:

tmesh = linspace(0,pi/2,5);
solinit = bvpinit(tmesh, @f);
sol = bvp4c(@odefun, @bcfun, solinit);
plot(sol.x, sol.y, '-o');

odefun.m:

function dzdt = odefun(t,z)
    dzdt = zeros(2,1);  
    dzdt = [z(2); z(1)];    
end

bcfun.m:

% boundary conditions
function res = bcfun(za, zb)
    res = [za(1); zb(2)-2];
end

f.m:

% Initial guess
function g = f(t)
    g = [sin(t) cos(t)];
end

[Titas Chattopadhyay]

Thank you so much.

[Ameer Hamza]

Glad to be of help.