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By Daniel Șuteu February 20, 2012

Find installed Perl modules matching a regular expression. It's very fast and efficient.

Download: https://github.com/trizen/perl-scripts/blob/master/Finders/locatepm

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Daniel Șuteu

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Popular posts from this blog

obmenu-generator

By Daniel Șuteu February 21, 2012

obmenu-generator is a simple, lightweight, easily configurable Perl script that generates a full Openbox XML-menu based upon the information present in *.desktop application files (related to fbmenugen and menutray).

It has full support for icons (respecting the current icon theme) and can generate either a static or a dynamic menu.

The parsing of the *.desktop files is provided by the Linux::DesktopFiles module.

In a dynamic menu, the entries are updated automatically when a new application is installed or when the current icon theme is changed by the user.

Starting with version 0.61, obmenu-generator introduced a new smart-cache system which will store all the required data from the *.destkop files in a new cache.db file, which is also updated automatically when a new application is (re)installed or when the config.pl or schema.pl are changed. With the new cache-system in place, a full menu with icons is generated in ~20ms (compared to ~60ms before).

In version 0.80, we introduced y…

alsi

By Daniel Șuteu August 10, 2012

alsi is a system information tool, designed for Arch Linux, related to archey and screenfetch, but more configurable.

All the configuration files are in: ~/.config/alsi

For example, to configure it for Gentoo, get the gentoo logo and put it in alsi.logo file, change something in alsi.output and alsi.conf files (if necessary) and then execute: alsi -f -l -c1=blue -c2=purple

Result:

1. Changing alsi.output:

my$b="\b\b\b\b";[{HARDCODED=>"\b\e[1;37m\e[41mTHIS IS ALSI\e[0m"},{OS=>$b.'%13sOS:%s %s'},# Operating system{HOSTNAME=>$b.'%4sHostname:%s %s'},# Hostname{UPTIME=>$b.'%9sUptime:%s %s'},# Uptime{KERNEL=>$b.'%9sKernel:%s %s'},# Kernel version{SHELL=>$b.'%10sShell:%s %s'},# Shell{PACKAGES=>$b.'%sPackages:%s %s'},# Number of installed packages{WM_DE=>$b."%13s%s:%s %s"},# WM or DE{GTK2_THEME=>$b.'%10sTheme:%s %s'},# Gtk2 theme{GTK2_ICON_THEME=>

menutray

By Daniel Șuteu February 21, 2012

Menutray is a simple menu generator (related to obmenu-generator and fbmenugen).

It generates a Perl script containing all the applications from the /usr/share/applications directory, ordered on categories. It also provides a schema file for customization.

Starting with version 0.42, menutray supports Gtk3 with the --gtk3 option.

Github: https://github.com/trizen/menutray
AUR Link: https://aur.archlinux.org/packages/menutray/

Youtube Viewer

By Daniel Șuteu March 02, 2012

# GTK Youtube Viewer This application came to life in 12 September 2010 as my first Gtk2/Glade learning project.

Its scope is to search and play YouTube videos in a native player. It comes with various search options; it can search for videos, playlists and/or channels. The videos are streamed directly in a selected video player at the best resolution (customizable) and with closed-captions (if available).

By default, it comes with support for three video players: MPV (recommended), MPlayer and VLC, but it allows the addition of more players inside the configuration file.

For a better experience, the application comes with built-in authentication support, using the OAuth 2.0 mechanism. After inserting the authentication token, a new tab will appear, named "My panel", which has the following buttons:
SubscriptionsFavorited videosLiked videosDisliked videosUploadsLog out
See also:
http://www.webupd8.org/2015/02/youtube-viewer-complete-youtube-client.html
# CLI Youtube Viewer Insi…

Is the Riemann hypothesis true?

By Daniel Șuteu November 09, 2016

In 2001, Jeffrey Lagarias proved that the Riemann hypothesis is equivalent to the following statement (proof here):

`\sigma(n) <= \H_n + \ln(\H_n)*\exp(\H_n)`
with strict inequality for `n > 1`, where `\sigma(n)` is the sum of the positive divisors of `n`.

In 1913, Grönwall showed that the asymptotic growth rate of the sigma function can be expressed by:

`\lim_{n to \infty}\frac{\sigma(n)}{\n \ln\ln n} = \exp(\gamma)`

where lim is the limit superior.

Relying on this two theorems, we can show that:

`lim_{n to \infty}\frac{\exp(\gamma) * n \ln \ln n}{\H_n + \ln(\H_n) * \exp(\H_n)} = 1`

with strict inequality for each `1 < n < \infty` (see Wolfram|Alpha):
`\exp(\gamma) * n \ln \ln n < \H_n + \ln(\H_n) * \exp(\H_n)`

If the Riemann hypothesis is true, then for each `n ≥ 5041`:

`\sigma(n) <= \exp(\gamma) * n \ln \ln n`
By using the usual definition of the `\gamma` constant:
`\gamma = \lim_{n to \infty}(\H_n - \ln n)`

we can reformulate the result as (see Wolfram|Alpha):

…

obbrowser

By Daniel Șuteu December 29, 2012

obbrowser is a very simple script which displays files and directories in the Openbox menu. It recursively browse the filesystem through openbox3 pipe menus. (related to fbrowse-tray)

The following line needs to be added inside the menu.xml file:
<menu id="obbrowser /my/dir" label="Disk" execute="obbrowser"/>

Or, if you are using the obmenu-generator, add the following line inside the schema.pl file:
{pipe => ['obbrowser /my/dir', 'Disk', 'drive-harddisk']},

The script supports a large variety of icons, thanks to File::MimeInfo and Linux::DesktopFiles modules.

Github: https://github.com/trizen/obbrowser
AUR link: https://aur.archlinux.org/packages/obbrowser/

Simple version, in C++:
https://github.com/trizen/cpp-learning/blob/master/openbox-pipefs.cpp

Simpler version, in Go:
https://github.com/trizen/go-learning/blob/master/openbox-pipefs.go

The beauty of Infinity

By Daniel Șuteu May 15, 2016

Infinity and its infinite beauty.

Today we're going to take a brief look at the beauty of infinity, through:

infinite sums infinite products continued fractions nested radicalsand limits
to represent some of the most well known and beautiful mathematical constants, like π, e and φ.

# Definitions Before diving into it, let's begin with some simple definitions:

1) Infinite sum:

`\sum_{n=1}^(\infty)\frac{1}{n} = \frac{1}{1} + \frac{1}{2} + \frac{1}{3} + \...`

2) Infinite product:

`\prod_{n=1}^(\infty)\frac{1}{n} = \frac{1}{1} * \frac{1}{2} * \frac{1}{3} * \...`

3) Continued fractions:

`\underset{n=1}{\overset{\infty}{\mathbf{K}}}\frac{1}{n} = \frac{1}{1 + \frac{1}{2 + \frac{1}{3 + \...}}}`

4) Nested radicals:

`\underset{n=1}{\overset{\infty}{\mathbf{R}}}(n + R)^(1/2) = \sqrt{1 + \sqrt{2 + \sqrt{3 + \...}}}`

5) Limit:

`\lim_{n to \infty}(1 + 1/n)^n = (1 + 1/n)^n`, where `n` approaches `\infty`.

# Infinite sums
`\sum_{n=0}^(\infty)\frac{1}{n!} = \e`

`\sum_{n=0}^(\infty)\frac{x^n}{n!} =…

fbmenugen

By Daniel Șuteu February 21, 2012

fbmenugen is a simple menu generator for the Fluxbox WM (related to menutray and obmenu-generator).

It generates a valid Fluxbox menu file with the applications from the /usr/share/applications directory, ordered on categories. It also provides a configuration file that allows the user to customize the menu.

Github: https://github.com/trizen/fbmenugen
AUR Link: https://aur.archlinux.org/packages/fbmenugen/

Mandelbrot set

By Daniel Șuteu January 17, 2017

The Mandelbrot set and its complex beauty.
# Formula At its simplest, the Mandelbrot set is defined iteratively by the following formula:

`z_(n+1) = (z_n)^2 + c`

# Generation The rules for generating the Mandelbrot set are surprisingly simple; we begin by defining the following three constants:

`W` = the width of the plane`H` = the height of the plane`Z` = the zoom factor
Then for each value of `x={1,2,...,W}` and `y={1,2,...,H}`, we create a complex number `c` as following:
`c = (2x - W) / (W*Z) + ((2y - H) / (H*Z))i`
The value of `c` is then assigned to a new variable, called `z_1`, as:
`z_1 = c`
Then we define a new constant, called `I`, which represents the total number of iterations that we want to perform (usually, in the range `[30,150]`).
`I = 100`
Then we choose a limit `L`, which will stop the iteration early if a certain value `|z_n|` (where `1 <= n <= I`) exceeds the value of `L`.
`L = 2`
Now we can begin the iteration, with `n={1,2,...,I}`.
`z_(n+1) = (z_n)^2 + c`
A…

Why 0÷0 doesn't have a value?

By Daniel Șuteu September 18, 2016

In this short post we're going to take a look at why `0/0` is really undefined.

# Overview It's an old mathematical issue, which has been debated many times over the centuries with mostly the same result: `0/0` does not have a defined value. But now, we're going to take a look at why this is true.

# Illustration To illustrate this, let's consider the following sum:

`\sum_{k=0}^(n)b^k = b^0 + b^1 + b^2 + ... + b^n`

Deriving a closed form to this sum, we get:

`\sum_{k=0}^(n)b^k = (b^(n+1) - 1) / (b-1)`

For example, when `b=3` and `n=4`, we have:

`3^0 + 3^1 + 3^2 + 3^3 + 3^4 = (3^(4+1) - 1) / (3-1)`

All good so far. However, if we set `b=1`, we have a special case:

`(1^(n+1) - 1) / (1-1) = 0/0`

We know that `1^k=1` for any `k>=0`, therefore:

`\sum_{k=0}^(n)1^k = n+1`

but when `b=1`, our closed-form evaluates to `0/0` for any value of `n`. From this we can conclude that `0/0` does not have a certain value.

Taking this example a little bit further, we can also show that…