Inverse of the Hilbert matrix
Syntax
H = invhilb(n)
Description
H = invhilb(n)
generates the exact inverse of the exact Hilbert matrix for n
less than about 15. For larger n
, invhilb(n)
generates an approximation to the inverse Hilbert matrix.
Limitations
The exact inverse of the exact Hilbert matrix is a matrix whose elements are large integers. These integers may be represented as floating-point numbers without roundoff error as long as the order of the matrix, n
, is less than 15.
Comparing invhilb(n)
with inv(hilb(n))
involves the effects of two or three sets of roundoff errors:
It turns out that the first of these, which involves representing fractions like 1/3 and 1/5 in floating-point, is the most significant.
Examples
invhilb(4)
is
16 -120 240 -140
-120 1200 -2700 1680
240 -2700 6480 -4200
-140 1680 -4200 2800
See Also
hilb
Hilbert matrix
References
[1] Forsythe, G. E. and C. B. Moler, Computer Solution of Linear Algebraic Systems, Prentice-Hall, 1967, Chapter 19.
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