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Added intergration of Monte Carlo for PHP #431

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Merged
merged 10 commits into from
Oct 7, 2018
Merged

Added intergration of Monte Carlo for PHP #431

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4bc5868
Added intergration of Monte Carlo for PHP
PudottaPommin Oct 3, 2018
b411169
Changed code style
PudottaPommin Oct 4, 2018
559c7fc
Update monte_carlo.php
PudottaPommin Oct 4, 2018
95eafaf
Update monte_carlo.php
PudottaPommin Oct 4, 2018
a7a3738
Update monte_carlo.php
PudottaPommin Oct 5, 2018
afa9d6d
Update monte_carlo.php
PudottaPommin Oct 6, 2018
ed52163
Update monte_carlo.php
PudottaPommin Oct 6, 2018
ec2f420
Update monte_carlo.php
PudottaPommin Oct 7, 2018
e3409c6
Merge branch 'master' into php_monte_carlo
PudottaPommin Oct 7, 2018
4a241aa
Styles fixes and typo
PudottaPommin Oct 7, 2018
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30 changes: 30 additions & 0 deletions contents/monte_carlo_integration/code/php/monte_carlo.php
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Original file line number Diff line number Diff line change
@@ -0,0 +1,30 @@
<?php
declare(strict_types=1);

function in_circle(float $positionX, float $positionY, float $radius = 1): bool
{
return pow($positionX, 2) + pow($positionY, 2) < pow($radius, 2);
}

function random_zero_to_one(): float
{
return mt_rand() / mt_getrandmax();
}

function monte_carlo(int $samples, float $radius = 1): float
{
$in_circle_count = 0;

for ($i = 0; $i < $samples; $i++) {
if (in_circle(random_zero_to_one() * $radius, random_zero_to_one() * $radius, $radius))
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Taken from PSR-2:

The body of each structure MUST be enclosed by braces. This standardizes how
the structures look, and reduces the likelihood of introducing errors as new
lines get added to the body.

$in_circle_count++;
}

return 4 * $in_circle_count / $samples;
}

$piEstimate = monte_carlo(100000000);
$percentError = abs($piEstimate - pi()) / pi() * 100;
echo sprintf('The estimate of PI is: %s', $piEstimate);
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  1. PHP has a printf function
  2. Probably should use %f for these values, php converts em anyway but no harm in being more correct.
  3. Why are we using PHP_EOL rather than \n, it doesn't work for single quote strings but they work fine in double quotes
    printf("The estimate of PI is: %f\n", $piEstimate);

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  1. it has, but there is not much difference and sprintf gives easier way to extract variable
  2. %f would generate X.XXXXX format when %s givex X.XX (depending on number of numbers after dot)
  3. PHP_EOL is constant depending on environment. from SO "PHP_EOL represents the endline character for the current system", so it's much prefered to use it

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Fair enough, I don't understand what you mean by "sprintf gives easier way to extract variable" but your other arguments make sense, I was under the impression PHP would \n to the correct line ending like C/C++.

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it's basically from my experience, where you don't print to console, but you need to work with strings, build them, etc. You can store sprintf to variable and work with it later. printf would print to output.

yes, it would but with PHP_EOL. otherwise if you specify \n it uses that, which might be problem on some platforms.

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@Butt4cak3 Butt4cak3 Oct 4, 2018 •
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You can store sprintf to variable and work with it later.

You do not do that, though, so there's no reason to use it. I have to agree with @Gorzoid here. printf() makes a little more sense.

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I give you this one, I'm gonna change it. But still I'm staying, that sprintf looks better 🤣

echo PHP_EOL;
echo sprintf('The percent error is: %s', $percentError);
4 changes: 4 additions & 0 deletions contents/monte_carlo_integration/monte_carlo_integration.md
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Expand Up @@ -71,6 +71,8 @@ each point is tested to see whether it's in the circle or not:
[import:1-4, lang:"ruby"](code/ruby/monte_carlo.rb)
{% sample lang="f90" %}
[import:1-8, lang:"fortran"](code/fortran/monte_carlo.f90)
{% sample lang="php" %}
[import:4-7, lang:"php"](code/php/monte_carlo.php)
{% endmethod %}

If it's in the circle, we increase an internal count by one, and in the end,
Expand Down Expand Up @@ -141,6 +143,8 @@ Feel free to submit your version via pull request, and thanks for reading!
[import, lang:"ruby"](code/ruby/monte_carlo.rb)
{% sample lang="f90" %}
[import, lang:"fortran"](code/fortran/monte_carlo.f90)
{% sample lang="php" %}
[import, lang:"php"](code/php/monte_carlo.php)
{% endmethod %}


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