Converting float decimal to fraction

Question

I am trying to convert calculations keyed in by users with decimal results into fractions. For e.g.; 66.6666666667 into 66 2/3. Any pointers? Thanx in advance

Answer 1

Sometimes it is necessary to treat only the decimals of a float. So I created a code that uses the function created by @Joni to present a format that is quite common in culinary recipes, at least in Brazil.

So instead of using 3/2 which is the result for 1.5, using the function I created it is possible to present the value 1 1/2, and if you want, you can also add a string to concatenate the values, creating something like "1 and 1/2 ".

function float2rat($n, $tolerance = 1.e-6) {
  $h1=1; $h2=0;
  $k1=0; $k2=1;
  $b = 1/$n;
  do {
      $b = 1/$b;
      $a = floor($b);
      $aux = $h1; $h1 = $a*$h1+$h2; $h2 = $aux;
      $aux = $k1; $k1 = $a*$k1+$k2; $k2 = $aux;
      $b = $b-$a;
  } while (abs($n-$h1/$k1) > $n*$tolerance);

  return "$h1/$k1";
}

function float2fraction($float, $concat = ' '){
  
  // ensures that the number is float, 
  // even when the parameter is a string
  $float = (float)$float;

  if($float == 0 ){
    return $float;
  }
  
  // when float between -1 and 1
  if( $float > -1 && $float < 0  || $float < 1 && $float > 0 ){
    $fraction = float2rat($float);
    return $fraction;
  }
  else{

    // get the minor integer
    if( $float < 0 ){
      $integer = ceil($float);
    }
    else{
      $integer = floor($float);
    }

    // get the decimal
    $decimal = $float - $integer;

    if( $decimal != 0 ){

      $fraction = float2rat(abs($decimal));
      $fraction = $integer . $concat . $fraction;
      return $fraction;
    }
    else{
      return $float;
    }
  }
}

Usage e.g:

echo float2fraction(1.5);
will return "1 1/2"