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/*
==============================================================================
This file is part of the JUCE library.
Copyright (c) 2017 - ROLI Ltd.
JUCE is an open source library subject to commercial or open-source
licensing.
By using JUCE, you agree to the terms of both the JUCE 5 End-User License
Agreement and JUCE 5 Privacy Policy (both updated and effective as of the
27th April 2017).
End User License Agreement: www.juce.com/juce-5-licence
Privacy Policy: www.juce.com/juce-5-privacy-policy
Or: You may also use this code under the terms of the GPL v3 (see
www.gnu.org/licenses).
JUCE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL WARRANTIES, WHETHER
EXPRESSED OR IMPLIED, INCLUDING MERCHANTABILITY AND FITNESS FOR PURPOSE, ARE
DISCLAIMED.
==============================================================================
*/
namespace juce
{
namespace dsp
{
/**
A class representing a polynomial
@tags{DSP}
*/
template <typename FloatingType>
class Polynomial
{
public:
//==============================================================================
/** Creates a new polynomial which will always evaluate to zero. */
Polynomial()
{
coeffs.add (0);
}
/** Creates a new polynomial with given coefficients.
@param numCoefficients The number of coefficients stored in coefficients.
This is also the order of the returned polynomial.
@param coefficients The coefficients which will be used by the newly
created polynomial. The Polynomial class will keep
a private copy of the coefficients.
*/
Polynomial (const FloatingType* coefficients, int numCoefficients)
: coeffs (coefficients, numCoefficients)
{
jassert (! coeffs.isEmpty());
}
/** Creates a copy of another polynomial. */
Polynomial (const Polynomial&) = default;
/** Creates a copy of another polynomial. */
Polynomial (Polynomial&&) = default;
/** Creates a copy of another polynomial. */
Polynomial& operator= (const Polynomial&) = default;
/** Creates a copy of another polynomial. */
Polynomial& operator= (Polynomial&&) = default;
/** Creates a new polynomial with coefficients by a C++11 initializer list.
This function can be used in the following way:
Polynomial<float> p ({0.5f, -0.3f, 0.2f});
*/
template <typename... Values>
Polynomial (Values... items) : coeffs (items...)
{
jassert (! coeffs.isEmpty());
}
//==============================================================================
/** Returns a single coefficient of the receiver for reading */
FloatingType operator[] (int index) const noexcept { return coeffs.getUnchecked (index); }
/** Returns a single coefficient of the receiver for modifying. */
FloatingType& operator[] (int index) noexcept { return coeffs.getReference (index); }
/** Evaluates the value of the polynomial at a single point x. */
FloatingType operator() (FloatingType x) const noexcept
{
// Horner's method
FloatingType y (0);
for (int i = coeffs.size(); --i >= 0;)
y = (x * y) + coeffs.getUnchecked(i);
return y;
}
/** Returns the order of the polynomial. */
int getOrder() noexcept
{
return coeffs.size() - 1;
}
//==============================================================================
/** Returns the polynomial with all its coefficients multiplied with a gain factor */
Polynomial<FloatingType> withGain (double gain) const
{
auto result = *this;
for (auto& c : result.coeffs)
c *= gain;
return result;
}
/** Returns the sum of this polynomial with another */
Polynomial<FloatingType> getSumWith (const Polynomial<FloatingType>& other) const
{
if (coeffs.size() < other.coeffs.size())
return other.getSumWith (*this);
auto result = *this;
for (int i = 0; i < other.coeffs.size(); ++i)
result[i] += other[i];
return result;
}
/** computes the product of two polynomials and return the result */
Polynomial<FloatingType> getProductWith (const Polynomial<FloatingType>& other) const
{
Polynomial<FloatingType> result;
result.coeffs.clearQuick();
auto N1 = coeffs.size();
auto N2 = other.coeffs.size();
auto Nmax = jmax (N1, N2);
auto N = N1 + N2 - 1;
for (int i = 0; i < N; ++i)
{
FloatingType value (0);
for (int j = 0; j < Nmax; ++j)
if (j >= 0 && j < N1 && i - j >= 0 && i - j < N2)
value = value + (*this)[j] * other[i - j];
result.coeffs.add (value);
}
return result;
}
private:
//==============================================================================
Array<FloatingType> coeffs;
JUCE_LEAK_DETECTOR (Polynomial)
};
} // namespace dsp
} // namespace juce
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