First input argument must be a function handle

Hello, Please!!!!! i need help. I'm trying to solve an integral function :

r=0:0.02:0.2;

d=[0.0005;0.001;0.0015;0.002;0.0025;0.003;0.0035;0.004;0.0045;0.005;0.0055];

fun={@(d,r) d.^3*exp(-4.1*(r.^(-0.21)*d))};

F=integral(fun,0.0005,0.0055);

But it returns : "First input argument must be a function handle"

Please how can i solve this problem?

Answer 1

[the cyclist]

There were a couple problems here.

First, you put your function in side a cell array (with the curly brackets), which is unnecessary, and is why MATLAB did not recognize fun as a function handle.

Second, you seem to want to do a double integral, but you used integral() rather than integral2().

Third, your function definition used matrix multiplication rather than element-wise multiplication in a couple places.

The following code fixes all of these problems, but I can't say for sure is what you intended to do:

fun=@(d,r) d.^3.*exp(-4.1.*(r.^(-0.21).*d));
F=integral2(fun,0.0005,0.0055,0,0.2);

Note that your pre-definition of r and d vectors is going to be ignored by integral2(). These two lines will execute on their own.

[nesrine nesrine]

Thank you but I have to integrate only the variable d

Answer 2

[nesrine nesrine]

Thanks i solved this problem

But i faced an other error in function plot :

fun=@(d,r) d.^3.*exp(-4.1.*(r.^(-0.21).*d));

F=integral2(fun,0.0005,0.0055,0,0.2);

L=((0.434*10^4*8*2100)/3)*F;

L1=distance*L;

ezplot(r,d,L); it seems that it's not the suitable function plot that i have to integrate. please helppp!!