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#ifndef __CGLA_ARITHSQMAT2X2FLOAT_H__
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#define __CGLA_ARITHSQMAT2X2FLOAT_H__
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#include "ExceptionStandard.h"
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#include "ArithSqMatFloat.h"
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namespace CGLA
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{
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  CGLA_DERIVEEXCEPTION(Mat2x2fException);
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  /** Two by two float matrix. This class is useful for various
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      vector transformations in the plane. */
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  template<class V, class M>
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  class ArithSqMat2x2Float: public ArithSqMatFloat<V,M, 2>
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  {
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  public:
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    /// Vector type
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    typedef V VectorType;
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    /// The type of a matrix element
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    typedef typename V::ScalarType ScalarType;
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  public:
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    /// Construct a Mat2x2f from two Vec2f vectors.
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    ArithSqMat2x2Float(V a, V b):
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      ArithSqMatFloat<V, M, 2> (a,b) {}
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    /// Construct a Mat2x2f from four scalars.
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    ArithSqMat2x2Float(ScalarType a, ScalarType b,
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		       ScalarType c, ScalarType d):
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      ArithSqMatFloat<V, M, 2>(V(a,b),V(c,d)) {}
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    /// Construct the NAN matrix
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    ArithSqMat2x2Float() {}
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    /// Construct a matrix from a single scalar value.
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    explicit ArithSqMat2x2Float(ScalarType a):
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      ArithSqMatFloat<V, M, 2>(a) {}
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  };
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  /** Compute the determinant of a Mat2x2f. This function is faster than
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      the generic determinant function for ArithSqMat */
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  template<class V, class M>
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  inline typename ArithSqMat2x2Float<V,M>::ScalarType
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  determinant(const ArithSqMat2x2Float<V,M> & m)
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  {
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    return m[0][0]*m[1][1]-m[0][1]*m[1][0];
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  }
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  template<class V, class M>
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  const M invert(const ArithSqMat2x2Float<V,M>& m)
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  {
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    typename M::ScalarType det = determinant(m);
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    if( !is_tiny(fabs(det)))
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      {
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	return M(m[1][1]/det, -m[0][1]/det,-m[1][0]/det, m[0][0]/det);
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      }
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    throw Mat2x2fException("Cannot invert matrix");
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  }
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}
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#endif