[fpc-pascal] fpc 32 / 64 bit / c++/ floating point question

Marco van de Voort marcov at stack.nl
Sun Nov 21 21:13:46 CET 2010

In our previous episode, Vinzent H?fler said:
> <mueller_michael at alice-dsl.net> wrote:
> > Single has 7 significant digits.
> <mode style="nitpicking">
> Six significant digits. The seventh already is unreliable.
> </mode>

A mistake in the nth digit can show up much higher than the nth or n-1th
digit, depending on the magnitude of the condition number.  

A commonly known case of an error in inputs propagating to large errors in
output is catastrophic cancellation, which can cause a
condition number >>1.  And the example _does_ add negative values to
positive ones, which is equal to the subtraction in catastrophic

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