Whoever begins writing a book on quantum mechanics is struck by the
breadth of the subject. In its applications first: atomic and molecular
p- sics, nuclear physics, optics, solid state physics, theory of gases
and liquids, elementary particles theory, almost all fields of
contemporary physics are based on quantum mechanics. In its formulation,
also, which borrows from many subfields of mathematics and reaches
philosophical reflection as much as modern technology. The writing
therefore implies, at the outset, making choices. I first chose to write
a book for those who strive to understand qu- tum mechanics. These are
physics students, of course, but also students and investigators in
theoretical chemistry, biophysics and engineering physics w- hing to
comprehend more deeply the computational methods they use. I have thus
tried to clarify delicate points rather than leave them aside.
Conceptual problems are treated in more detail than in most general
textbooks. But understanding also involves the capability to perform
concrete calculations. This motivates the development of numerical
methods which, most of the time, are the only ones that yield
quantitative results. I chose also to present quantum mechanics as a
self-contained theory. The exposition largely develops around the
central notion of state space.