Can you loop in math mode?urn:uuid:5f54300a-e852-79e3-fd76-ecec3f741d2c2019-11-19T09:36:05ZSebastian Gniazdowskisgniazdowski@gmail.comCan you loop in math mode?2019-08-19T00:17:14Zurn:uuid:9127c648-c48b-1b41-75e0-af63a48f8e07
```Hello,
is some kind of a looping possible in math mode?

--
Sebastian Gniazdowski
IRC: https://kiwiirc.com/client/chat.freenode.net:+6697/#zplugin
Blog: http://zdharma.org
```
Stephane Chazelasstephane.chazelas@gmail.comRe: Can you loop in math mode?2019-08-19T06:21:18Zurn:uuid:bccb91aa-ebf6-e8e7-b6a3-99aa10c744a6
```2019-08-19 02:16:20 +0200, Sebastian Gniazdowski:
[...]
> is some kind of a looping possible in math mode?
[...]

Can you maybe be more specific as to what you're trying to do?

You can use recursion:

\$ n=6 a='(n-->1 ? a*(n+1) : 1)' zsh -c 'echo \$((a))'
720

(6!)

Including via math functions, but within limits.

\$ n=0 a='(++n <= 255 ? a+2 : 1)' zsh -c 'echo \$((a))'
zsh:1: math recursion limit exceeded: (++n <= 255 ? a+2 : 1)

And you can of course have command substitutions inside an
arithmetic expression:

\$ echo \$(( 1 \$(for i ({2..6}) print "*\$i") ))
720

--
Stephane
```
Sebastian Gniazdowskisgniazdowski@gmail.comRe: Can you loop in math mode?2019-08-19T06:42:14Zurn:uuid:98a4dc6b-571c-5192-3e47-38f3ea13dae9
```I'm writing a function that computes lengths of the lines in BUFFER
and builds up an array, where each element is a sum of the previous
and the current line / element.

So I have:

integer idx sum
lines_lengths=( \${lines_lengths[@]/(#m)*/\$(( sum += \${#MATCH}+1 ))} )

However, I would also like to take into account screen lines, so i.e.
gradually decline \${#MATCH} by COLUMNS bit by bit, assigning a new
element also for each screen-line. Like the following function does:

.zed-compute-llen() {
len=\${#1}
while (( len > COLUMNS )) {
sum+=COLUMNS
lines_lengths[++idx]=( \$sum )
len=len-COLUMNS
}
sum+=len+1
lines_lengths[++idx]=( \$sum )
}

So basically, I would want to do this in the // substitution, like so:

: \${lines_lengths[@]/(#m)*/\$(( append(\${#MATCH}) ))}

which now thus just resolved :] I don't even need the string-math
function, append should add multiple lines_lengths elements if len >
COLUMNS, that's all.

But thanks for the answer, I think I could use recursion for this too.

On Mon, 19 Aug 2019 at 08:20, Stephane Chazelas
<stephane.chazelas@gmail.com> wrote:
>
> 2019-08-19 02:16:20 +0200, Sebastian Gniazdowski:
> [...]
> > is some kind of a looping possible in math mode?
> [...]
>
> Can you maybe be more specific as to what you're trying to do?
>
> You can use recursion:
>
> \$ n=6 a='(n-->1 ? a*(n+1) : 1)' zsh -c 'echo \$((a))'
> 720
>
> (6!)
>
> Including via math functions, but within limits.
>
> \$ n=0 a='(++n <= 255 ? a+2 : 1)' zsh -c 'echo \$((a))'
> zsh:1: math recursion limit exceeded: (++n <= 255 ? a+2 : 1)
>
> And you can of course have command substitutions inside an
> arithmetic expression:
>
> \$ echo \$(( 1 \$(for i ({2..6}) print "*\$i") ))
> 720
>
> --
> Stephane

--
Sebastian Gniazdowski
IRC: https://kiwiirc.com/client/chat.freenode.net:+6697/#zplugin
Blog: http://zdharma.org
```
Sebastian Gniazdowskisgniazdowski@gmail.comRe: Can you loop in math mode?2019-08-19T06:44:30Zurn:uuid:191bf8ab-2284-2716-a7b9-c6cefb47b0d6
```On Mon, 19 Aug 2019 at 08:41, Sebastian Gniazdowski
<sgniazdowski@gmail.com> wrote:
> lines_lengths=( \${lines_lengths[@]/(#m)*/\$(( sum += \${#MATCH}+1 ))} )

The line should say:
lines_lengths=( \${lines[@]/(#m)*/\$(( sum += \${#MATCH}+1 ))} )

> : \${lines_lengths[@]/(#m)*/\$(( append(\${#MATCH}) ))}

The same – the line should say:
: \${lines[@]/(#m)*/\$(( append(\${#MATCH}) ))}
```