CommonTrig.h

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#ifndef INCLUDE_MOLASSEMBLER_COMMON_TRIG_H
#define INCLUDE_MOLASSEMBLER_COMMON_TRIG_H

#include "Molassembler/DistanceGeometry/ValueBounds.h"
#include "Molassembler/Modeling/BondDistance.h"

#include <cmath>

namespace Scine {
namespace Molassembler {
namespace CommonTrig {

using ValueBounds = DistanceGeometry::ValueBounds;

template<typename T>
T lawOfCosines(const T a, const T b, const T phiRadians) {
  return std::sqrt(
    a * a
    + b * b
    - 2 * a * b * std::cos(phiRadians)
  );
}

template<typename T>
T lawOfCosinesAngle(
  const T a,
  const T b,
  const T c
) {
  double ratio = (
    a * a
    + b * b
    - c * c
  ) / (
    2 * a * b
  );

  /* Accept ratios a little above one for the sake of numerical inaccuracies
   * when the triangle almost doesn't exist
   */
  if(ratio > 1 && std::fabs(ratio - 1) <= 1e-10) {
    return 0.0;
  }

  return std::acos(ratio);
}

template<typename T>
T lawOfSinesAngle(
  const T a,
  const T alphaRadians,
  const T b
) {
  return std::asin(
    b * std::sin(alphaRadians) / a
  );
}

double dihedralLength(
  double a,
  double b,
  double c,
  double alpha,
  double beta,
  double dihedral
);

ValueBounds dihedralLengthBounds(
  const ValueBounds& aBounds,
  const ValueBounds& bBounds,
  const ValueBounds& cBounds,
  const ValueBounds& alphaBounds,
  const ValueBounds& betaBounds,
  const ValueBounds& dihedralBounds
);

} // namespace CommonTrig
} // namespace Molassembler
} // namespace Scine

#endif