Re: Math expression evaluation error?

[Vincent Lefevre <vincent@vinc17.net>]

On 2015-01-09 22:40:34 +0000, Peter Stephenson wrote:
> diff --git a/Doc/Zsh/arith.yo b/Doc/Zsh/arith.yo
> index a620b73..5c334ce 100644
> --- a/Doc/Zsh/arith.yo
> +++ b/Doc/Zsh/arith.yo
> @@ -233,6 +233,15 @@ necessary.  In addition, if any operator which requires an integer
>  equivalents with assignment) is given a floating point argument, it will be
>  silently rounded down to the next integer.
>  
> +Users should beware that, in common with many other programming
> +languages but not software designed for calculation, the evaluation of
> +an expression in zsh is taken a term at a time and promotion of integers
> +to floating point does not occur in terms only containing integers.  A
> +typical result of this is that a division such as tt(6/8) is truncated,
> +in this being rounded down to 0.  The tt(FORCE_FLOAT) shell option can
> +be used in scripts or functions where floating point evaluation is
> +required throughout.

This explanation is incorrect (or very ambiguous). FORCE_FLOAT doesn't
force a floating-point evaluation; it just converts *constants* to
floating-point. See the differences:

ypig% setopt FORCE_FLOAT
ypig% integer a=1 b=2
ypig% echo $((1/2))
0.5
ypig% echo $((a/b))
0

I'm wondering whether this is the expected behavior, though.

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Vincent Lefèvre <vincent@vinc17.net> - Web: <https://www.vinc17.net/>
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