It shows: Undefined function 'permute' for input arguments of type 'function_handle' when i solve the double integration with trapezoidal method. Can I know how to solve this?

clear all
clc
Q=((2000*42*(3.785*10^-3))/(1*24*3600)); %volumetric flowrate of fluid in m3/s
D=(4*0.0254); %inner diameter of pipe in m
A=(pi()*(D^2))/4; %cross sectional area of pipe in m2
uave=Q/A; %average velocity in m/s
R=D/2; %radius of the pipe in m
radius=[0:0.0002:R];
dita=[0:pi():2*pi()];
[RADIUS,DITA]=meshgrid(radius,dita);
F=@(RADIUS,DITA) RADIUS.*(1-((RADIUS./R).^2));
I=trapz(dita,trapz(radius,F,2));
%umax is the maximum velocity in m/s
umax=uave/I
%u is the velocity of pipe in m/s
u=umax*(1-((radius./R).^2));

[madhan ravi]

F=@(RADIUS,DITA) RADIUS.*(1-((RADIUS./R).^2));

Why did you create a function handle with DITA it's used nowhere in the line?

In the next line you don't evaluate the function handle.

What's the reason for creating a function handle?

[Sylvia Tan]

Thanks for your reply.

DITA will become a variable after it undergoes integration. F is the function where it has not undergone any integration so it does not appear in the equation.

Thank you.