Why does my integral not work without the command "global"

function y=integrand1(t)
%UNTITLED3 Summary of this function goes here
%   Detailed explanation goes here
global a k
y=a.*t.^k;
end

%Mainprogram
clc
clear all
global a k
%%
a=1;
k=1;
T=1;
q=integral(@integrand1,0,T);

%%
a=2;
k=1;
T=1;
b=integral(@integrand1,0,T);

%%
a=1;
k=2;
T=1;
c=integral(@integrand1,0,T);

%%
a=1;
k=1;
T=2;
d=integral(@integrand1,0,T);

%%
disp('answers for the integrals are: ')
disp([q     b     c       d])

so my question is, how come the code won't work if i just remove the global command?

I have tried only crunching the first integral while getting rid of the Global command in both the function file and the main script but nop o.O

I'm curios as to what the global command actually does, the description is kinda hard to understand, maybe im super dumb.

Anyhow thanks on advance!

Answer 1

[Matt J]

To get rid of global, implement as follows

a=1;
k=1;
T=1;
q=integral(@(t)a.*t.^k,0,T);

[Matt J]

Or, you could do

a=1;
k=1;
T=1;
q=integral(@(t)integrand1(t,a,k) ,0,T);

with

function y=integrand1(t,a,k)  %<---modified
 y=a.*t.^k;
end

[Aldin Hodzic]

Awesome! Thank you <3