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/* ----------------------------------------------------------------------- *
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* This file is part of GEL, http://www.imm.dtu.dk/GEL
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* Copyright (C) the authors and DTU Informatics
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* For license and list of authors, see ../../doc/intro.pdf
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* ----------------------------------------------------------------------- */
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/** @file ArithSqMat2x2Float.h
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* abstract 2x2 floating point matrix class
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*/
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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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/** \brief Two by two float matrix template.
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This class template is useful for various vector transformations
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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
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