graphing with a matrix using matlab

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

Answer 1

[Mohith Kulkarni]

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.