avatarConstantin Stan

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Abstract

7d">Dart</h2><p id="2594">The console Dart only version I wrote when I first had the idea is:</p><div id="8ea5"><pre><span class="hljs-keyword">import</span> <span class="hljs-string">'dart:math'</span> <span class="hljs-keyword">as</span> <span class="hljs-built_in">Math</span>;</pre></div><div id="b136"><pre>double kTonTNTInJoules <span class="hljs-operator">=</span> <span class="hljs-number">4184000000000</span><span class="hljs-comment">;</span> double c <span class="hljs-operator">=</span> <span class="hljs-number">299792458</span><span class="hljs-comment">;</span> int fatMan <span class="hljs-operator">=</span> <span class="hljs-number">21</span><span class="hljs-comment">;</span></pre></div><div id="8461"><pre><span class="hljs-built_in">Function</span> E = <span class="hljs-function"><span class="hljs-params">(double m)</span> =></span> m * <span class="hljs-built_in">Math</span>.pow(c, <span class="hljs-number">2</span>);</pre></div><div id="1ea8"><pre><span class="hljs-built_in">num</span> joulesToKTonTNT(<span class="hljs-built_in">num</span> val) => val/(kTonTNTInJoules*fatMan);</pre></div><div id="5b83"><pre><span class="hljs-function"><span class="hljs-keyword">void</span> <span class="hljs-title">main</span>()</span> {

<span class="hljs-built_in">double</span> yourCatsWeight = <span class="hljs-number">4.1</span>; <span class="hljs-comment">//in kg</span> print(<span class="hljs-string">'Your cat has ${joulesToKTonTNT(E(yourWeight)).toStringAsFixed(2)} times more explosive energy than a bomb that destroyed an entire city…'</span>);

}</pre></div><p id="d188">Above we first import the Dart’s core math library then define some constants: the number of Joules in one kiloton of TNT (<b>T</b>ri<b>N</b>itro<b>T</b>oluene) — <b>kTonTNTInJoules</b>, a better approximation of the speed of light — <b>c</b>, and the number of kilotons of TNT that a well known atomic bomb had — <a href="https://en.wikipedia.org/wiki/Fat_Man"><b>fatMan</b></a>.</p><p id="bf90">We then define the function that will calculate <b>mc²</b></p><p id="0306">We also define a function that will transform the energy (measured in Joules) into kilotons of TNT.</p><p id="61db">In the <b>main</b> body I defined my cat’s weight and displayed the result:</p><div id="8000"><pre>Your <span class="hljs-keyword">cat</span> has 4193.86 times <span class="hljs-keyword">more</span> explosive energy than a bomb that destroyed <span class="hljs-keyword">an</span> entire city…</pre></div><p id="c40c">The DartPad version can be played with <a href="https://dartpad.dev/97476531a0d5723f143700003c01f1ba">here</a>:</p><div id="bc84" class="link-block"> <a href="https://dartpad.dev/97476531a0d5723f143700003c01f1ba"> <div> <div> <h2>Your Explosive Energy </h2> <div><h3>Dart Edition</h3></div> <div><p>dartpad.dev</p></div> </div> <div> <div style="background-image: url(https://miro.readmedium.com/v2/resize:fit:320/)"></div> </div> </div> </a> </div><h2 id="9e26">Flutter</h2><p id="7ce

Options

9">Moving on to Flutter, the code becomes:</p> <figure id="5220"> <div> <div>

            <iframe class="gist-iframe" src="/gist/Constans/bcae948ad353fcc6813ed23e3f06e4b0.js" allowfullscreen="" frameborder="0" height="undefined" width="undefined">
          </div>
        </div>
    </figure></iframe></div></div></figure><p id="e998">Regarding the logic behind it, the code goes about the same as the previous one.</p><p id="8a1a">I changed the example to use the most powerful atomic bomb to be ever detonated in the history of human kind: the <a href="https://en.wikipedia.org/wiki/Tsar_Bomba">Tsar Bomba</a>.</p><p id="25d4">I also provided with the option to switch weight units between <b>kilograms</b> (kg) and <b>pounds</b> (lbs). When the pounds unit is chosen the weight must be first converted in kilograms and that is what the <b>getMass</b> function does.</p><figure id="e96b"><img src="https://cdn-images-1.readmedium.com/v2/resize:fit:800/1*9x8j2L58QRLNaf0Uw3Safg.png"><figcaption></figcaption></figure><p id="3638">The result is displayed either when pressing on the <b>Calculate</b> button, or when <b>Enter</b> key is pressed and the weight input is in focus.</p><figure id="347c"><img src="https://cdn-images-1.readmedium.com/v2/resize:fit:800/1*BBC_N5NWOQdWgAWgCCTMNA.png"><figcaption></figcaption></figure><p id="11f8">The DartPad version can be played with <a href="https://dartpad.dev/bcae948ad353fcc6813ed23e3f06e4b0">here</a> (using Google Chrome is recommended):</p><div id="b5b1" class="link-block">
      <a href="https://dartpad.dev/bcae948ad353fcc6813ed23e3f06e4b0">
        <div>
          <div>
            <h2>Your Explosive Energy</h2>
            <div><h3>Flutter Edition</h3></div>
            <div><p>dartpad.dev</p></div>
          </div>
          <div>
            <div style="background-image: url(https://miro.readmedium.com/v2/resize:fit:320/)"></div>
          </div>
        </div>
      </a>
    </div><p id="edef">If you want to read more about functions in Dart, you can do that <a href="https://readmedium.com/fluttering-dart-b37110f4d1bf">here</a>:</p><div id="af3b" class="link-block">
      <a href="https://readmedium.com/fluttering-dart-b37110f4d1bf">
        <div>
          <div>
            <h2>Fluttering Dart: Functions</h2>
            <div><h3>How to write, use and abuse functions in Dart</h3></div>
            <div><p>medium.com</p></div>
          </div>
          <div>
            <div style="background-image: url(https://miro.readmedium.com/v2/resize:fit:320/1*88Gz2J-Hje09d7geYn752A.jpeg)"></div>
          </div>
        </div>
      </a>
    </div><p id="9bfa">I hope this example got you intrigued and you’ll calculate the explosive energy you’ve stored inside of you.</p><p id="a0c1">Next time you feel tired just think of that. :)</p><figure id="bf0f"><img src="https://cdn-images-1.readmedium.com/v2/resize:fit:800/1*aeDRwVZtvT8quFeVrSZMhA.jpeg"><figcaption></figcaption></figure><p id="204a">Tha(nk|t’)s all!</p></article></body>

Fluttering Dart

Your Explosive Energy

Use Flutter or Dart to unveil it

Photo by Rafki Altoberi on Unsplash

A while back I’ve started a journey called Fluttering Dart in which I explored Dart programming language fundamentals one must get in touch with, in order to build robust Flutter applications.

It’s a journey that most people with a bit of programming experience can take.

When I got to explore functions in Dart, the first thing that came to my mind to use as an example was Albert Einstein’s famous formula:

E = mc²

It states that the energy (E) can be calculated as the mass (m) multiplied by the speed of light (c) squared.

I started to search for a nice way to present the formula and translate it into a Dart function and stumbled upon this:

The physics and math behind are explained very well in the above article and I’ll be focusing on writing and explaining the equivalent code.

When I first had the idea I was thinking to use DartPad. At that time it supported only the Dart code. Meanwhile, DartPad evolved and now can also run Flutter code which will make things nicer.

Dart

The console Dart only version I wrote when I first had the idea is:

import 'dart:math' as Math;
double kTonTNTInJoules = 4184000000000;
double c = 299792458;
int fatMan = 21;
Function E = (double m) => m * Math.pow(c, 2);
num joulesToKTonTNT(num val) => val/(kTonTNTInJoules*fatMan);
void main() {
  
  double yourCatsWeight = 4.1; //in kg
  print('Your cat has ${joulesToKTonTNT(E(yourWeight)).toStringAsFixed(2)} times more explosive energy than a bomb that destroyed an entire city…');
  
}

Above we first import the Dart’s core math library then define some constants: the number of Joules in one kiloton of TNT (TriNitroToluene) — kTonTNTInJoules, a better approximation of the speed of light — c, and the number of kilotons of TNT that a well known atomic bomb had — fatMan.

We then define the function that will calculate mc²

We also define a function that will transform the energy (measured in Joules) into kilotons of TNT.

In the main body I defined my cat’s weight and displayed the result:

Your cat has 4193.86 times more explosive energy than a bomb that destroyed an entire city…

The DartPad version can be played with here:

Flutter

Moving on to Flutter, the code becomes:

Regarding the logic behind it, the code goes about the same as the previous one.

I changed the example to use the most powerful atomic bomb to be ever detonated in the history of human kind: the Tsar Bomba.

I also provided with the option to switch weight units between kilograms (kg) and pounds (lbs). When the pounds unit is chosen the weight must be first converted in kilograms and that is what the getMass function does.

The result is displayed either when pressing on the Calculate button, or when Enter key is pressed and the weight input is in focus.

The DartPad version can be played with here (using Google Chrome is recommended):

If you want to read more about functions in Dart, you can do that here:

I hope this example got you intrigued and you’ll calculate the explosive energy you’ve stored inside of you.

Next time you feel tired just think of that. :)

Tha(nk|t’)s all!

Dart
Flutter
Programming
Flutter Web
Energy
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