Function for computing sin of a input radian value

sin.scss

@import 'factorial';

$PI: 3.14159265358979323846;
$TWO_PI: $PI * 2;
$HALF_PI: $PI / 2;
$QUARTER_PI: $PI / 4;
$SIN_ITERATION: 10;

@function sin($rad) {
  // Ensure value is between 0 to TWO_PI
  $normalisedRad: $rad % $TWO_PI;
  @if $normalisedRad < 0 {
    $normalisedRad: $normalisedRad + $TWO_PI;
  }
  
  // Known whole numbers to return without computing
  @if $normalisedRad == 0 or $normalisedRad == $PI {
    @return 0;
  } 
  @if $normalisedRad == $HALF_PI {
    @return 1;     
  }
  
  // Memorise squared rad val to reduce recomputation
  $radSquare: $normalisedRad * $normalisedRad;
  $radPowAccVal: $normalisedRad;
   
  $factorialCounter: 1;
  $factorialAccVal: 1;
    
  $totalVal: $normalisedRad;
  
  // Iteratively compute an approx value
  @for $i from 0 to $SIN_ITERATION {
    $radPowAccVal: $radPowAccVal * -$radSquare;
    $factorialAccVal: factorial($factorialCounter + 2, $factorialCounter, $factorialAccVal);
    $factorialCounter: $factorialCounter + 2;
    
    $totalVal: $totalVal + ($radPowAccVal / $factorialAccVal);
  }
    
  @return $totalVal;
}