Gustavo Enrique Jimenez wrote:
2009/10/18 Tom Verhoeff <t.verho...@tue.nl>:
A simple example is the situation where one needs to calculate
the replacement resistor value R for parallel resistors having
values R1, R2, ..., Rk. The formula is R = 1/(1/R1 + 1/R2 + ... + 1/Rk).
The formula gives a divide-by-zero if one of the resistors has value 0.
But in that case, the replacement value R also equals 0. When allowing
infinities, it just works out fine (infinity + x = infinity, 1/infty = 0).
That is precisely why IEEE 754 has infinities. Also see
<http://www.cs.berkeley.edu/~wkahan/ieee754status/why-ieee.pdf>
for other examples and further motivation.
Mmm... the formula R = 1/(1/R1 + 1/R2 + ... + 1/Rk) is only valid if
none of Rn=0.
Programmers can and must take care of that situation.
Agree: treating 1/0 as you would treat a finite number makes me feel
uncomfortable. See for instance
http://www.cocoa.uk.com/?p=63
Frank
_______________________________________________
fpc-pascal maillist - fpc-pascal@lists.freepascal.org
http://lists.freepascal.org/mailman/listinfo/fpc-pascal
