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accsum_wilkinson

A test vector by Wilkinson.

Calling Sequence

x = accsum_wilkinson ( r )

Parameters

r :

a 1-by-1 matrix of doubles, a positive integer

x :

a 1-by-r, matrix of doubles

Description

Returns a vector x of size 2^r where r is a flint. Exercise 4.2 in SNAA

Examples

// Example with r = 3
x = accsum_wilkinson (3)
// Expected result
e = [1 , 1-%eps , 1-2*%eps , 1-2*%eps , 1-4*%eps , 1-4*%eps , 1-4*%eps , 1-4*%eps]'

// Use with larger r
x = accsum_wilkinson(10);
s=sum(x)
[s,e] = accsum_compsum ( x )
[s,e] = accsum_dblcompsum ( x )

Authors

Bibliography

"Stability and numerical accuracy of algorithms", Nicolas Higham

"Handbook of Floating Point Computations", Muller et al


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