The principal part at of a function
is the portion of the Laurent series consisting of terms with negative degree. That is,
is the principal part of at . has an essential singularity at, if and only if the principal part is an infinite sum.
Famous quotes containing the words principal and/or part:
“For me, the principal fact of life is the free mind. For good and evil, man is a free creative spirit. This produces the very queer world we live in, a world in continuous creation and therefore continuous change and insecurity. A perpetually new and lively world, but a dangerous one, full of tragedy and injustice. A world in everlasting conflict between the new idea and the old allegiances, new arts and new inventions against the old establishment.”
—Joyce Cary (1888–1957)
“A mother wants all of life to be painless for her child. This is not a realistic goal, however. Deprivation and frustration are as much a part of life as gratification. It is some balance between these that a mother is looking for. To take the next step is always painful in part. It means relinquishing gratification on some level. If one is totally gratified where one is, why move ahead? If one is totally frustrated, why bother?”
—Elaine Heffner (20th century)