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Accsum >> Accsum > Support > accsum_sumcond

accsum_sumcond

Condition number of the sum function.

Calling Sequence

s = accsum_sumcond ( x )
[s,c] = accsum_sumcond ( x )

Parameters

x :

a m-by-n, matrix of doubles

s :

a 1-by-1, matrix of doubles, the sum

c :

a 1-by-1, matrix of doubles, the condition number

Description

Condition number of the sum function.

Examples

// A straightforward example of an ill-conditionned data for the sum.
xl = 10^(1:15);
x = [-xl xl+0.1];
sum(x)
[s,c] = accsum_sumcond(x)
for o = 1 : 8
xo = accsum_order ( x , o );
[s,e] = accsum_dcs ( xo );
disp([o s e])
end

Authors

Bibliography

"Stability and numerical accuracy of algorithms", Nicolas Higham

"Handbook of Floating Point Computations", Muller et al


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