Global Variables

Global Variables

If you want more than one function to share a single copy of a variable, simply declare the variable as global in all the functions. Do the same thing at the command line if you want the base workspace to access the variable. The global declaration must occur before the variable is actually used in a function. Although it is not required, using capital letters for the names of global variables helps distinguish them from other variables. For example, create a new function in a file called falling.m:

function h = falling(t)
global GRAVITY
h = 1/2*GRAVITY*t.^2;

Then interactively enter the statements

global GRAVITY
GRAVITY = 32;
y = falling((0:.1:5)');

The two global statements make the value assigned to GRAVITY at the command prompt available inside the function. You can then modify GRAVITY interactively and obtain new solutions without editing any files.