Prev: howto: Calling MATLAB from C - returning values?
Next: Control Theory PID tuning
From: Eamonn B on 5 Apr 2010 14:18
Ok I have two function, One does a calculation based on the the Second functions variable depending on the result a value will be assigned to a variable inside function One. But it doesnt update its self and just keeps replacing the value held in the variable.

function turn = %%gets points from function 2

does cal

if cal is > something
turn = [turn 1]

else
turn = [turn -1]

but it does append to its self and just replaces the value

anyone know what I am doing wrong?
From: James Tursa on 5 Apr 2010 14:34
"Eamonn B" <pakblue11(a)gmail.com> wrote in message <hpd9gs$aus$1(a)fred.mathworks.com>...
> Ok I have two function, One does a calculation based on the the Second functions variable depending on the result a value will be assigned to a variable inside function One. But it doesnt update its self and just keeps replacing the value held in the variable.
>
> function turn = %%gets points from function 2
>
> does cal
>
> if cal is > something
> turn = [turn 1]
>
> else
> turn = [turn -1]
>
> but it does append to its self and just replaces the value
>
> anyone know what I am doing wrong?

Yes. Your problem is that you didn't post any real m-code for us to look at and debug.

James Tursa
From: Eamonn B on 5 Apr 2010 15:32
I have changed some of the code since posting but it still does the samething
Function 1
function [turn] = crossTurn(x0,y0,x1,y1,x2,y2)
prevPoints = [];

cross = ((x2-x0)*(y1-y0))-((x1-x0)*(y2-y0));

if(cross==0)
turn = [prevPoints 0];

elseif(cross<0)
turn = [prevPoints -1];

elseif(cross>0)
turn = [prevPoints 1];
end
end

%%%%%%%%%%%%%%%%%%%%%

Function 2
function convex
a = [[5 2 1 4 -1 12 9 13 14]' [6 3 10 3 -5 6 4 4 3]']; % [x] [y]
..
..
..
..
for i=3:length(a)
.
.
.
uLength = length(upper);
turn = crossTurn(upper(uLength-5),upper(uLength-4),upper(uLength-3),upper(uLength-2),upper(uLength-1),upper(uLength))

end

end
%%%%%%%%%%%%%%%%%%%
From: TideMan on 5 Apr 2010 15:57
On Apr 6, 7:32 am, "Eamonn B" <pakblu...(a)gmail.com> wrote:
> I have changed some of the code since posting but it still does the samething
> Function 1
> function [turn] = crossTurn(x0,y0,x1,y1,x2,y2)
> prevPoints = [];
>
> cross = ((x2-x0)*(y1-y0))-((x1-x0)*(y2-y0));
>
> if(cross==0)
>         turn = [prevPoints 0];
>
> elseif(cross<0)
>         turn = [prevPoints -1];
>
> elseif(cross>0)
>         turn = [prevPoints 1];
> end
> end
>
> %%%%%%%%%%%%%%%%%%%%%
>
> Function 2
> function convex
> a = [[5 2 1 4 -1 12 9 13 14]' [6 3 10 3 -5 6 4 4 3]']; % [x] [y]
> .
> .
> .
> .
>  for i=3:length(a)
>    .
>    .
>    .    
>      uLength = length(upper);
>      turn = crossTurn(upper(uLength-5),upper(uLength-4),upper(uLength-3),upper(uLength-2),upper(uLength-1),upper(uLength))
>
>  end
>
> end
> %%%%%%%%%%%%%%%%%%%

But the 2nd function has no output and the index i appears to do
nothing.
turn is simply overwritten in each loop.
You probably need to make turn a vector.

BTW, i is a poor choice for index because it resets sqrt(-1).
From: Eamonn B on 5 Apr 2010 16:13
I deleted some of the code in the second function

There are two points in upper and i appends the next point to upper.

Whats the difference between an array and a vector?
 |  Next  |  Last
Pages: 1 2
Prev: howto: Calling MATLAB from C - returning values?
Next: Control Theory PID tuning