If you mean you have polynomials with coefficients defined in x1 and x2 - for example the values in x1 would yield:
y = 1*x^3 + 2*x^2 + 3*x + 4;
Then you would sum the coefficients by pre-padding the array(s) of polynomial coefficients that are of smaller order. Example:
Create array of polynomial coefficients:
x1 = 1:4;
x2 = 5:10;
Create and save a new Matlab function:
function coeff_sum = sum_poly_coeff(x1, x2)
x1_order = length(x1);
x2_order = length(x2);
if x1_order > x2_order
max_order = size(x1);
else
max_order = size(x2);
end
new_x1 = padarray(x1,max_order-size(x1),0,'pre');
new_x2 = padarray(x2,max_order-size(x2),0,'pre');
coeff_sum = new_x1 + new_x2;
return
You can run this from the command line and view results by:
x3 = sum_poly_coeff(x1, x2);
x = 0:0.1:10;
plot(x,polyval(x1,x),'b-',x,polyval(x2,x),'r-',x,polyval(x3,x),'g-');
Or if you just want to see the result, you don't even have to create a function. Just do this at the command line:
x = 0:0.1:10;
plot(x,polyval(x1,x),'b-',x,polyval(x2,x),'r-',x,polyval(x1,x)+polyval(x2,x),'g-');
