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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.

When a menu with icons is generated, the GDBM_File module will be used for storing the icon paths, giving us a big performance boost. This functionality is implemented inside the Linux::DesktopFiles module.

The icon database is 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 is changed. With the new cache-system in place, a full m…

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…

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/

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

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/

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!} =…

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…

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…