The informal name for the classical Handbook of Mathematical Functions with Formulas, Graphs, and Mathematical Tables. As it predates Tcl by about a quarter of a century, there is no direct Tcl connection (though there is the NIST connection), but being a classical reference, it gets mentioned every now and then when something numerical is done on this wiki. Hence some pointers for those who do not themselves own a copy may be useful.
The original book can be viewed online at [L1 ]. See also the Wikipedia article [L2 ].
The successor to this book is the Digital Library of Mathematical Functions [L3 ] of BIG SCIENCE: National Institute of Standards and Technology, but that is currently (2008) rather far from complete.