Re: [Issue 4111] New: Foreach ranges accept floating-point extrema

[bearophile]

Aelxx:
> >foreach(i; 2.1 .. 4.10001) {
> >writeln(typeid(typeof(i))); // Output: double
> >break;
> >}
> 
> I'd like MATLAB style more:
> foreach (f; linspace (0.0, 1.0, 100))
> {...}
> here f gets values 0, 0.0101.., 0.0202..., ..., 0.98989..., 1.0
> 
> foreach (f; logspace (1.0, 1e6, 7))
> {...}
> here f gets values 1e0, 1e1, 1e2, 1e3, 1e4, 1e5, 1e6. 

If you have comments on a bug report, it's quite better if you write them in 
Bugzilla, because here they will probably be lost/ignored.
Phobos has iota() that's similar to what you ask, a FP version is easy to 
create.

Bye,
bearophile

Re: [Issue 4111] New: Foreach ranges accept floating-point extrema

[Aelxx]

>foreach(i; 2.1 .. 4.10001) {
>writeln(typeid(typeof(i))); // Output: double
>break;
>}

I'd like MATLAB style more:
foreach (f; linspace (0.0, 1.0, 100))
{...}
here f gets values 0, 0.0101.., 0.0202..., ..., 0.98989..., 1.0

foreach (f; logspace (1.0, 1e6, 7))
{...}
here f gets values 1e0, 1e1, 1e2, 1e3, 1e4, 1e5, 1e6. 

[Issue 4111] New: Foreach ranges accept floating-point extrema

[d-bugmail]

http://d.puremagic.com/issues/show_bug.cgi?id=4111

   Summary: Foreach ranges accept floating-point extrema
   Product: D
   Version: future
  Platform: All
OS/Version: All
Status: NEW
  Keywords: accepts-invalid
  Severity: normal
  Priority: P2
 Component: DMD
AssignedTo: nob...@puremagic.com
ReportedBy: bearophile_h...@eml.cc


--- Comment #0 from bearophile_h...@eml.cc 2010-04-21 14:01:40 PDT ---
This D2 code works with dmd 2.043, it shows that foreach accepts floating point
extrema too.

But I think it's safer/tidier to accept only ranges with integral extrema (in
Python too the range/xrange expects integers). FP approximations can cause
problems here.


import std.stdio;
import std.math: nextUp;
void main() {
foreach(i; 2.1 .. 4.10001) {
writeln(typeid(typeof(i))); // Output: double
break;
}
foreach(i; 2.1 .. nextUp(4.1))
write(i, " "); // Output: 2.1 3.1 4.1
}

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