static size_t FFTStretch(Polynomial<T> & p)
{
size_t n = 1;
size_t d = p.Degree();
while (1)
{
if (d <= n)
break;
n <<= 1;
if (n == 0)
Polynomial<T>::Xoverflow();
}
n <<= 1;
p = p.Stretch(n);
return n;
}
bool Polynomial::Divide(const Polynomial & divisor_polynomial,
Polynomial & quotient_polynomial,
Polynomial & remainder_polynomial) const
{
//------------------------------------------------------------------
// If the divisor is zero then fail.
//------------------------------------------------------------------
int divisor_degree = divisor_polynomial.Degree();
bool non_zero_divisor_flag = ((divisor_polynomial.Degree() != 0)
|| (divisor_polynomial[0] != 0.0));
if (non_zero_divisor_flag)
{
//--------------------------------------------------------------
// If this dividend polynomial's degree is not greater than
// or equal to the divisor polynomial's degree then do the division.
//--------------------------------------------------------------
remainder_polynomial = *this;
int dividend_degree = Degree();
quotient_polynomial = 0.0;
int quotient_maximum_degree = dividend_degree - divisor_degree + 1;
quotient_polynomial.SetLength(quotient_maximum_degree);
quotient_polynomial.m_degree = -1;
double * quotient_coefficient_ptr =
quotient_polynomial.m_coefficient_vector_ptr;
double * dividend_coefficient_ptr =
remainder_polynomial.m_coefficient_vector_ptr;
double leading_divisor_coefficient = divisor_polynomial[divisor_degree];
//--------------------------------------------------------------
// Loop and subtract each scaled divisor polynomial
// to perform the division.
//--------------------------------------------------------------
int dividend_index = dividend_degree;
for (dividend_index = dividend_degree;
dividend_index >= divisor_degree;
--dividend_index)
{
//----------------------------------------------------------
// Subtract the scaled divisor from the dividend.
//----------------------------------------------------------
double scale_value = remainder_polynomial[dividend_index] / leading_divisor_coefficient;
//----------------------------------------------------------
// Increase the order of the quotient polynomial.
//----------------------------------------------------------
quotient_polynomial.m_degree += 1;
int j = 0;
for (j = quotient_polynomial.m_degree; j >= 1; --j)
{
quotient_coefficient_ptr[j] = quotient_coefficient_ptr[j - 1];
}
quotient_coefficient_ptr[0] = scale_value;
//----------------------------------------------------------
// Subtract the scaled divisor from the dividend.
//----------------------------------------------------------
int dividend_degree_index = dividend_index;
for (j = divisor_degree; j >=0; --j)
{
dividend_coefficient_ptr[dividend_degree_index] -= divisor_polynomial[j] * scale_value;
--dividend_degree_index;
}
}
//--------------------------------------------------------------
// Adjust the order of the current dividend polynomial.
// This is the remainder polynomial.
//--------------------------------------------------------------
remainder_polynomial.AdjustPolynomialDegree();
quotient_polynomial.AdjustPolynomialDegree();
}
else
{
quotient_polynomial = DBL_MAX;
remainder_polynomial = 0.0;
}
return non_zero_divisor_flag;
}
