sin - PHP code example

PHP Function Sin - Calculating Sine Trigonometry

The php function sin is one of the important functions for calculating trigonometry problems. It returns the sine of the number passed to it as its only parameter in radians.

PHP is loosely typed, meaning that it doesn’t have to know what the variable you are passing in has a specific data type. But if you want to pass a variable into a function that expects a specific data type, you can use the word global before the name of the variable in the function definition. This will create a new entry in the PHP symbol table that references an internal data structure that contains the variables value and type. This will scope the variable so that it is visible both inside and outside of the function.

Another feature that allows for flexible code is the ability to call a function without any parameters. If you don’t specify a return value, the function will simply exit as soon as it has completed its work. The spr() and str() functions are great examples of this type of function.

There are other useful functions in the PHP math library, including exp($value) and log($value, $base). For example, if you need to calculate the logarithm of an integer in base 10 you can use the function log10($value).

sin example

// radiant conversion for coordinates         $radLatitude  = $location['latitude']   * $halfCircle / 180;
        $radLongitude = $location['longitude']  * $halfCircle / 180;

        // get solar coordinates         $tmpRise       = $rise ? $quarterCircle : $threeQuarterCircle;
        $radDay        = $this->date('z',$this->_unixTimestamp) + ($tmpRise - $radLongitude) / $fullCircle;

        // solar anomoly and longitude         $solAnomoly    = $radDay * 0.017202 - 0.0574039;
        $solLongitude  = $solAnomoly + 0.0334405 * sin($solAnomoly);
        $solLongitude += 4.93289 + 3.49066E-4 * sin(2 * $solAnomoly);

        // get quadrant         $solLongitude = $this->_range($solLongitude, $fullCircle);

        if (($solLongitude / $quarterCircle) - intval($solLongitude / $quarterCircle) == 0) {
            $solLongitude += 4.84814E-6;
        }

        // solar ascension         $solAscension = sin($solLongitude) / cos($solLongitude);

$imprecision = 0;
      $correction = 0;
    }
    else {
      $imprecision = -0.00001;
      $correction = 0.5;
    }

    // Do the trigonometry, applying imprecision fixes where needed.     $rad = deg2rad($angle);
    $cos = cos($rad);
    $sin = sin($rad);
    $a = $this->width * $cos;
    $b = $this->height * $sin + $correction;
    $c = $this->width * $sin;
    $d = $this->height * $cos + $correction;
    if ((int) $angle == $angle && in_array($angle, [60, 150, 300])) {
      $a = $this->fixImprecision($a, $imprecision);
      $b = $this->fixImprecision($b, $imprecision);
      $c = $this->fixImprecision($c, $imprecision);
      $d = $this->fixImprecision($d, $imprecision);
    }