Class: Fixnum

Inherits:
Integer show all
Defined in:
ext/factorials/factorials.c

Instance Method Summary collapse

Instance Method Details

#double_factorial ⇒ Object 



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# File 'ext/factorials/factorials.c', line 22

VALUE factorials_num_double_factorial(VALUE num)
{
  long value = NUM2INT(num), result = 1;

  if(value % 2 == 0) {
    result = pow(2, value / 2) * factorial(value / 2);
  } else {
    result = factorial(value) / (pow(2, (value - 1) / 2) * factorial((value - 1) / 2));
  }

  return INT2NUM(result);
}

#factorial ⇒ Object 



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# File 'ext/factorials/factorials.c', line 15

VALUE factorials_num_factorial(VALUE num)
{
  long value = NUM2INT(num);

  return INT2NUM(factorial(value));
}

#superfactorial ⇒ Object 



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# File 'ext/factorials/factorials.c', line 35

VALUE factorials_num_superfactorial(VALUE num)
{
  long value = NUM2INT(num), result = 1, i;

  for(i = 1; i <= value; i++) {
    result = result * factorial(i);
  }

  return INT2NUM(result);
}