International PHP Conference 2019 - Spring Edition

sin

(PHP 4, PHP 5, PHP 7)

sin正弦

说明

float sin ( float $arg )

sin() 返回参数 arg 的正弦值。参数 arg 的单位为弧度。

参数

arg

单位是弧度的值。

返回值

arg 的正弦值

范例

Example #1 sin() 例子

<?php

// 返回值的精度由配置中的 precision 指示确定
echo sin(deg2rad(60));  //  0.866025403 ...
echo sin(60);           // -0.304810621 ...

?>

参见

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User Contributed Notes 1 note

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-6
gerjoo at gmail dot com
8 years ago
You can use SIN & COS to create/draw circles.

Please beware that the circle's center is also your base point (0,0). So without specifying an offset, some coordinates will be negative.

<?php

$circleRadius
= 70;
$offsetX      = 100;
$offsetY      = 100;

for(
$i = 0; $i <= 360; ++$i) {
   
$x = round(cos($i * M_PI / 180) * $circleRadius);
   
$y = round(sin($i * M_PI / 180) * $circleRadius);
   
   
// Draw some pixel, or do something else here.
   
imagesetpixel($GDimage, $x + $offsetX, $y + $offsetY, $GDcolor);
}

?>
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