Function definition are not supported in this context. Functions can only be created as local or nested functions in code files

I keep getting this error from 'function vf = collision(v0,next)':

Function definition are not supported in this context. Functions can only be created as local or nested functions in code files.

Here is my code:

clear % clear all variables in the workspace

global m

v = input('enter initial velocities of three cart in [a,b,c] format ');

m = input('enter mass of three cart in [a,b,c] format ');

threshold = input('enter the threshold for energy and momentum checks');

E0 = sum((1/2)*m.*vi.^2); % initial energy before collision, in erg

P0 = sum(m.*vi); % initial momentum before collision, in g*cm/s

count = 0; % initialize a collision counter

while v(1) > v(2) || v(2) > v(3)

count = count + 1; % update collision counter

if v(1) > v(2)

next = 12; % if false, skip to the next IF

end

if v(2) > v(3)

next = 23; % if false, then next = 12

end

if v(1) > v(2) && v(2) > v(3)

next = input('Which carts collide next, 12 or 23? ');

% if false, next = 12 or 23, depending on first two IF statements

end

% output collision # and final velocity

fprintf('There are %u collisions', count)

v = collision(v, next)

% check energy and momentum... output only if there is a problem...

Check_E = E0 - sum(m*(1/2).*v.^2) % Check shoud be zero

Check_P = P0 - sum(m.*v) % Check should be zero

if Check_E > threshold || Check_P > threshold

disp('There is a problem with checks')

Check_E

Check_P

end

end

if count == 0

disp('There is no collision')

else

disp('There are no more collisions')

% ----- define functions -----

function vf = collision(v0,next)

global m

if next == 12

% final velocity of cart#1,in cm/s

vf(1) = ((m(1) -m(2))*v0(1) + 2*m(2)*v0(2))/(m(1) + m(2));

% final velocity of cart#2, in cm/s

vf(2) = (2*m(1)*v0(1) + (m(2)-m(1))*v0(2))/(m(1) + m(2));

vf(3) = v0(3);

end

if next == 23

vf(1) = v0(1);

% final velocity of cart#2, in cm/s

vf(2) = ((m(2)-m(3))*v0(2) + 2*m(3)*v0(3))/(m(2) + m(3));

% final velocity of cart#3, in cm/s

vf(3) = (2*m(2)*v0(2) + (m(3)-m(2))*v0(3))/(m(2) + m(3));

end

end

Answer 1

[DGM]

In versions which support local functions in scripts (R2021x does), the functions must be at the end of the file. There aren't enough end statements to make the structure unambigous, but you appear to have the function definition inside of an if-else structure. Either way, just make sure that the function definitions are the last thing in the file and are not inside any other scope.

[Mingkai Xiang]

thank you so much, I actually missed a end after a if statement. Than you sir