Please help me sir i am stuck in matlab with a program. Sir, I am using MATLAB 2015a while running a program as below for I get an error like this "Error: Function definitions are not permitted in this context."

function dhdt = tankfill(t,h)
A = 10 + 4*sin(t);
H = 2*sqrt(h); 
dhdt = A - H;
tspan = [0 30];
h0 = 1; 
[t,h] = ode45(tankfill,tspan,h0);
plot(t,h)

Error: Function definitions are not permitted in this context.

Answer 1

[Walter Roberson]

You need to store the first four lines of that code in a file named tankfill.m, but the lines starting from the assignment to tspan should either go into a different file or should go on the command line.

In R2015a it was never valid to try to define a function at the command line, and it was never valid to try to define a function inside a script file (a script file is any .m file whose first executable line is not 'function' or 'classdef'). A later MATLAB release made it possible to define functions inside script files in some circumstances, but even in the very latest versions it is never valid to define a function at the command line.

[Sanjiv Kumar]

Sir still the problem exists. Please help me if you can write the program fully and send it to me, it would be a real help to me.

[Walter Roberson]

function drive_a_tank

tspan = [0 30];
h0 = 1; 
[t,h] = ode45(@tankfill,tspan,h0);
plot(t,h)

store the above in the file drive_a_tank.m

function dhdt = tankfill(t,h)
A = 10 + 4*sin(t);
H = 2*sqrt(h); 
dhdt = A - H;

store this code in the file tankfill.m

To execute the code, go to the command line and command

drive_a_tank

[Sanjiv Kumar]

No progress sir, Again same error is annoying me. please do something . Its a humble request

[Walter Roberson]

Create a new directory. Unzip the attached file into that directory. Inside MATLAB, cd to that directory. At the command line give the command

drive_a_tank