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)
“In this nation I see tens of millions of its citizens, a substantial part of its whole population, who at this very moment are denied the greater part of what the very lowest standards of today call the necessities of life. I see one third of a nation ill-housed, ill-clad, ill-nourished. The test of our progress is not whether we add more to the abundance of those who have much, it is whether we provide enough for those who have too little.”
—Franklin D. Roosevelt (1882–1945)