I keep getting this error in Matlab:
Attempted to access r(0,0); index must be a positive integer or logical.
Error in ==> Romberg at 15
I ran it with Romberg(1.3, 2.19,8)
I think the problem is the statement is not logical because I made it positive and still got the same error. Anyone got some ideas of what i could do?
function Romberg(a, b, n)
h = b - a;
r = zeros(n,n);
for i = 1:n
h = h/2;
sum1 = 0;
for k = 1:2:2^(i)
sum1 = sum1 + f(a + k*h);
end
r(i,0) = (1/2)*r(i-1,0) + (sum1)*h;
for j = 1:i
r(i,j) = r(i,j-1) + (r(i,j-1) - r(i-1,j-1))/((4^j) - 1);
end
end
disp(r);
end
function f_of_x = f(x)
f_of_x = sin(x)/x;
end
There are two lines where you're using 0 to index, which you can't in Matlab:
r(i,0) = (1/2)*r(i-1,0) + (sum1)*h;
and
r(i,j) = r(i,j-1) + (r(i,j-1) - r(i-1,j-1))/((4^j) - 1);
when j==1 or i==1.
I suggest that you run your loops starting from 2, and replace the exponents i and j with (i-1) and (j-1), respectively.
As an aside: You could write the loop
for k = 1:2:2^(i)
sum1 = sum1 + f(a + k*h);
end
as
k = 1:2:2^i;
tmp = f(a + k*h);
sum1 = sum(tmp);
if you write f_of_x as
sin(x)./x
在MATLAB中,向量和矩阵从1开始编制索引。因此,代码的第一行无效,因为r
上的索引为0。
You have zero subscripts in
r(i,0) = (1/2)*r(i-1,0) + (sum1)*h;
This is impossible in MATLAB -- all indices start form 1.
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