How to get coefficients for second degree polynomial with only two given boundary conditions (means with two equations but with three coefficients)?
20 次查看(过去 30 天)
显示 更早的评论
I have Energy displacement numeric data in which Energy follows second degree polynomial (Ax^2+Bx+C) as given below;
x (disp) = [ 0 1 2 3]; E (energy) = [0 1 4.5 10.5];
Consider first point x = 0 and 1, gives
0 = C1;
1 = A1+B1+C1;
Consider second point x = 1 and 2, gives
1 = A2+B2+C2;
4.5 = 4A2+2B2+C2;
But I have two equations with three coefficients, is there anyway numeric approximation method in matlab to solve for three coefficients with two equations?
0 个评论
回答(1 个)
David Goodmanson
2022-4-9
编辑:David Goodmanson
2022-4-9
Hi Ankit,
x = [ 0 1 2 3];
E = [0 1 4.5 10.5];
c = polyfit(x,E,2) % fit a quadratic
E1 = polyval(c,x)
figure(1)
plot(x,E,'o-',x,E1)
grid on
c =
1.2500 -0.2500 -0.0000
polyfit fits a quadratic (resulting coefficients are in c) to the four points in a least squared error sense. It so happens that the four points exactly fit the resulting quadratic.
0 个评论
另请参阅
类别
在 Help Center 和 File Exchange 中查找有关 Quadratic Programming and Cone Programming 的更多信息
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!