Saving the variables in a function call and using them next time the same function is called

I call a function few times within a loop. Each time the function is called it calculates the value of dx,dy and AF. The next time the same function is called I need to compare the dx and dy as calculated in previous call with the ones calculated in this call and if (dx_previous =dx_new and dy_previous =dy_new) then I need to put AF= AF_previous+AF_new.

Can someone please help me with this. How do I do it

Answer 1

[Sean de Wolski]

Use a persistent variable or a nested function.

http://www.mathworks.com/help/releases/R2013b/matlab/ref/persistent.html

http://www.mathworks.com/help/releases/R2013b/matlab/matlab_prog/share-data-between-workspaces.html#f0-50984

[Mahi Nazir]

Thanks! persistent variable did the job

Answer 2

[Azzi Abdelmalek]

k=1
[dx,dy,AF]=youy_fcb(~)
A(k,:)=[dx dy AF];
k=k+1
[dx,dy,AF]=youy_fcb(~)
A(k,:)=[dx dy AF];
d=A(end,:)-A(en-1,:)
dx=d(1)
dy=d(2)
AF=d(3)

[Mahi Nazir]

Thanks a lot for your reply... But sorry I didn't get it... I am a beginner, can u please provide some explanation to the above.

Thanks for your time

[Azzi Abdelmalek]

Suppose after calling your function

dx=1;
dy=2;
AF=20

k=1
A(k,:)=[dx dy AF]  % store your data in the first row of A

% When you call your function another time and find for example

dx=5;
dy=10;
AF=55;

% increment k and do

k=k+1
A(k,:)=[dx dy AF]

% check your matrix A, it contains 2 rows

d=A(end,:)-A(en-1,:) % will find the difference between the last row and the previous row

and so on

[Mahi Nazir]

I want the function I am calling should be doing all this because it will be plotting at the end.... Like if previous dx and new dx are same and prev dy and new dy are same the AF will be accumulated (Previous_AF + new AF) and the plot3(dx,dy,AF)... This all needs to be done in the function I am calling

[Azzi Abdelmalek]

function [dx,dy,AF]=your_fcn(~)
persistent old_dx old_dy old_AF
if isempty(old_x)
  old_dx=0  % initialize
  old_dy=0
  old_AF=0
end
% your code
dx=f(old_dx,...)
dy=f(old_dy,...)
AF=f(old_AF,...)
old_dx=dx;
old_dy=dy
old_AF=AF