% least_ft.m
% Min int_a^b |f(x)-p(x)|^2 dx
% input funtion form : f = @(x) exp(x);
function main(n,a,b,f)
% p(x) = a1 + a2*x + a3*x2 : degree (n-1) polynomial
if nargin==0
n=3;a=-1;b=1;f = @(x) exp(x);
elseif nargin==1
a=-1;b=1;f = @(x) exp(x);
elseif nargin==3
f = @(x) exp(x);
end
A = zeros(n,n); F = zeros(n,1);
for i=1:n
for j=1:n
Q = @(x) x.^(i+j-2);
A(i,j) = quad(Q,a,b);
end
Q = @(x) f(x).*(x.^(i-1));
F(i) = quad(Q,a,b);
end
u = A\F;
xv = linspace(a,b,201);
fx = f(xv); px = zeros(size(xv));
for i=1:n
px = px + u(i)*xv.^(i-1);
end
plot(xv,fx,'b-',xv,px,'r-')
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이름검색
행렬과 Matlab 1
Near Minimax interpolation 
