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/* Copyright (c) 2008-2022 the MRtrix3 contributors.
*
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/.
*
* Covered Software is provided under this License on an "as is"
* basis, without warranty of any kind, either expressed, implied, or
* statutory, including, without limitation, warranties that the
* Covered Software is free of defects, merchantable, fit for a
* particular purpose or non-infringing.
* See the Mozilla Public License v. 2.0 for more details.
*
* For more details, see http://www.mrtrix.org/.
*/
#ifndef __math_hermite_h__
#define __math_hermite_h__
#include <limits>
#include "types.h"
namespace MR
{
namespace Math
{
template <typename T> class Hermite
{ NOMEMALIGN
public:
using value_type = T;
Hermite (value_type tension = 0.0) : t (T (0.5) *tension) { }
void set (value_type position) {
value_type p2 = position*position;
value_type p3 = position*p2;
w[0] = (T (0.5)-t) * (T (2.0) *p2 - p3 - position);
w[1] = T (1.0) + (T (1.5) +t) *p3 - (T (2.5) +t) *p2;
w[2] = (T (2.0) +T (2.0) *t) *p2 + (T (0.5)-t) *position - (T (1.5) +t) *p3;
w[3] = (T (0.5)-t) * (p3 - p2);
}
value_type coef (size_t i) const {
return (w[i]);
}
template <class S>
S value (const S* vals) const {
return (value (vals[0], vals[1], vals[2], vals[3]));
}
template <class S>
S value (const S& a, const S& b, const S& c, const S& d) const {
return (w[0]*a + w[1]*b + w[2]*c + w[3]*d);
}
private:
value_type w[4];
value_type t;
};
}
}
#endif
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