Competitive Programming

/**
 * Author: Per Austrin, Ulf Lundstrom
 * Date: 2009-04-09
 * Source:
 * Description:\\
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 Apply the linear transformation (translation, rotation and scaling) which takes line p0-p1 to line q0-q1 to point r.
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\vspace{-8mm}
\includegraphics[width=\textwidth]{../content/geometry/linearTransformation}
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 * Status: not tested
 */
#pragma once

#include "Point.h"

typedef Point<double> P;
P linearTransformation(const P& p0, const P& p1,
		const P& q0, const P& q1, const P& r) {
	P dp = p1-p0, dq = q1-q0, num(dp.cross(dq), dp.dot(dq));
	return q0 + P((r-p0).cross(num), (r-p0).dot(num))/dp.dist2();
}