projection matrix

Noun

 * 1)  A transformation matrix whose associated transformation is a projection.
 * 2) * 2006, H. Watari, Y. Shimoyama, Chapter 5: Density Matrix Formalism of Angular Momentum in Multi-Quantum Magnetic Resonance, Christopher J. Bender, Lawrence Berliner (editors, Computational and Instrumental Methods in EPR, Springer, page 191,
 * The resultant eigenvalues of the angular momentum are independent of direction, but the projection matrices are dependent.
 * 1)  A matrix that maps a vector of response (dependent variable) values to a vector of fitted or predicted values.
 * 1)  A matrix that maps a vector of response (dependent variable) values to a vector of fitted or predicted values.