How can I make a variable defined in one script make change also in a second script?

MOTIVATION: I wrote the following lines to obtain the distance of a give moving point between two images:

open cpcorr.m;
P2=4;

base_points_0 = [ 75  24 ];
input_points_0 =[ 75  24 ];

imagea = imread('0.bmp');     
imageb = imread('1.bmp'); 
image1 = rgb2gray(imagea);    
image2 = rgb2gray(imageb);    
y = zeros(1,2,4);          
[input_points, base_points] = cpselect(image2,image1, input_points_0, base_points_0, 'wait', true);
y(:,:,1) = base_points;              

corrected_inputs = cpcorr(input_points, base_points, image2, image1);  
y(:,:,2) = corrected_inputs;          
input_points = corrected_inputs;
base_points = corrected_inputs;
filename1 = '1.bmp';

PROBLEM: The value 4 of variable P2 should be assigned to the correlation size (CORRSIZE = P2) in cpcorr.m but unfortunately I obtain the following error:

??? Undefined function or variable 'P2'.

Error in ==> cpcorr at 76
CORRSIZE = P2;

QUESTION: How can I write a value in the calculation script that makes a change in cpcorr.m without needing to change that number manually?

Thank you for your help

Emerson

Answer 1

[Junaid]

Hi,

use global variables.

declare p2 as global.

http://www.mathworks.co.jp/help/techdoc/ref/global.html