Sharing Variables Between Parent and Nested Functions
In general, variables in one function workspace are not available to other functions. However, nested
functions can access and modify variables in the workspaces of the functions that contain them.
This means that both a nested function and a function that contains it can modify the same variable
without passing that variable as an argument. For example, in each of these functions, main1 and
main2, both the main function and the nested function can access variable x:
function main1
x = 5;
nestfun1
function nestfun1
x = x + 1;
end
end
function main2
nestfun2
function nestfun2
x = 5;
end
x = x + 1;
end
When parent functions do not use a given variable, the variable remains local to the nested function.
For example, in this function named main, the two nested functions have their own versions of x that
cannot interact with each other:
function main
nestedfun1
nestedfun2
function nestedfun1
x = 1;
end
function nestedfun2
x = 2;
end
end
Functions that return output arguments have variables for the outputs in their workspace. However,
parent functions only have variables for the output of nested functions if they explicitly request them.
For example, this function parentfun does not have variable y in its workspace:
function parentfun
x = 5;
nestfun;
function y = nestfun
y = x + 1;
end
end
If you modify the code as follows, variable z is in the workspace of parentfun:
function parentfun
x = 5;
z = nestfun;
function y = nestfun
20 Function Basics
20-28