# Writing expression for summation on mathlab

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Prince Igweze on 1 Dec 2019
Answered: Mack Duffy on 1 Dec 2019 how can i write this on mathlab

#### 1 Comment

Ajay Kumar on 1 Dec 2019
Have you tried it before asking the question? If not please do try first.
You can use for loops for iterating i.e. j from 1 to N and to iterate other variables.
and I see nothing except that in the equation, you can use basic built-in functions in matlab to perform squareroot(sqrt) operations.
for squaring you can always use ^2 or .^2 for element wise squaring.
doc for
doc sqrt

Mack Duffy on 1 Dec 2019
This is the summation for the midpoint numerical integration method. This is an example of how to turn a summation into matlab code. Hope this helps somewhat.
function [Y] = midpoint_integration(A,B,N,S)
D = (A-B)/N;
W = str2func(['@(X)' S]);
Y=0;
for i = 0:(N-1)
Y = Y + W((B+D/2)+i*D);
end
Y = Y*D;
U = error_midpoint(A,B,N,S);
answer_output = (' \n \n The area under the curve is %4.2f and the error bounds is %4.2f \n');
end
%A is the upper bound
%B is the lower bound
%N is the number of of sub intervals
%S is the function you want to integrate