@TECHREPORT\{IMM2004-03271,
    author       = "P. C. Hansen",
    title        = "Oblique projections, pseudoinverses, and standard-form  transformations",
    year         = "2004",
    keywords     = "Oblique projection, oblique pseudoinverse, weighted pseudoinverse",
    number       = "",
    series       = "IMM-Technical report- 2004-13",
    institution  = "Informatics and Mathematical Modelling, Technical University of Denmark, {DTU}",
    address      = "Richard Petersens Plads, Building 321, {DK-}2800 Kgs. Lyngby",
    type         = "",
    url          = "http://www2.compute.dtu.dk/pubdb/pubs/3271-full.html",
    abstract     = "Standard-form transformation is a technique for transforming a discrete ill-posed problem in general form (with a seminorm as regularizing term) into a standard-form problem. We give a simple geometric explanation why the weighted pseudoinverse is the correct inverse to use in the standard-form transformation. Our presentation is based on oblique projections and oblique pseudoinverses - tools that are often overlooked in numerical analysis."
}