# graphing with a matrix using matlab

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Khang Nguyen on 22 Nov 2020
Edited: Mohith Kulkarni on 25 Nov 2020
If I have a reduce normal form Matrix on matlab for example A = [ 1 0 0 3 ; 0 1 0 6 ; 0 0 1 5]
I want to graph it in an equation y = a + bx +cx^2 where a = 3 , b = 6 and c = 5(3,6,5 is the last value in the matrix above). How should i do this. I am trying to solve the lease square problem in linear algebra.
Can you please give me an advice of how to write a code to do this if the matrix increasing.
Thank you

Mohith Kulkarni on 25 Nov 2020
Edited: Mohith Kulkarni on 25 Nov 2020
To plot the equation, refer to the code below.
A = [1 0 0 3; 0 1 0 6; 0 0 1 5]
B = A(:,end) %last column for a,b,c
x = linspace(1,10,10); %initializing x values
y = zeros(10,1)'; %initializing y values
deg = size(A,2)-2;
for idx = 0:deg
y = y+ B(idx+1)*(x.^idx);
end
plot(y,x)
For solving system of linear equations using least squares method, refer to lsqr.
You can also check polyfit for polynomial curve fitting.