src/Mutator/ReturnValue/FloatNegation.php
public static function getMutation(array &$tokens, $index)
    {
        $tokenCount = count($tokens);
        for ($i=$index+1; $i < $tokenCount; $i++) {
            if (is_array($tokens[$i]) && $tokens[$i][0] == T_WHITESPACE) {
                continue;
            } elseif (is_array($tokens[$i]) && $tokens[$i][0] == T_DNUMBER) {
                // Dump the negation - string for negative ints
                if (self::getPreviousToken($tokens, $i) == '-') {
                    $tokens[$i-1] = [
                        T_WHITESPACE,
                        ''
                    ];
                    break;
                }
                // otherwise multiply by -1 to make negative for positive ints
                $num = (float) $tokens[$i][1];
                $replace = -1 * $num;
                $tokens[$i] = [
                    T_DNUMBER,
                    sprintf("%.2f", $replace)
                ];
                break;
            }
        }
    }
public static function getMutation(array &$tokens, $index)
    {
        $tokenCount = count($tokens);
        for ($i=$index+1; $i < $tokenCount; $i++) {
            if (is_array($tokens[$i]) && $tokens[$i][0] == T_WHITESPACE) {
                continue;
            } elseif (is_array($tokens[$i]) && $tokens[$i][0] == T_DNUMBER) {
                // Dump the negation - string for negative ints
                if (self::getPreviousToken($tokens, $i) == '-') {
                    $tokens[$i-1] = [
                        T_WHITESPACE,
                        ''
                    ];
                    break;
                }
                // otherwise multiply by -1 to make negative for positive ints
                $num = (float) $tokens[$i][1];
                $replace = -1 * $num;
                $tokens[$i] = [
                    T_DNUMBER,
                    sprintf("%.2f", $replace)
                ];
                break;
            }
        }
    }
Replace any float with its sign inverted (i.e. multiply by -1)

@param array $tokens
@param int $index
@return array