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A note on properties of condition numbers

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Clovis C. Gonzaga, Hugo J. Lara

The condition numbers described by Stewart, Todd and others
for a matrix $ A $ are given by the suprema of the norms of
all the oblique projection operators respectively on the image
space of $ A^T $ and the null space of $ A $. This paper shows
that these two numbers coincide.

Department of Mathematics, Federal University of Santa Catarina,
Cx. Postal 5210, 88040-970 Florianopolis, SC, Brazil