For real parameters alpha >= 0 and beta > 1, consider the weight function
w(x) = x^alpha exp(-x^beta) on (0, infinity).
The n-point Gaussian quadrature rule for this weight is the unique choice of nodes x_1 < ... < x_n in (0, infinity) and positive weights w_1, ..., w_n such that
integral from 0 to infinity of f(x) w(x) dx = w_1 f(x_1) + ... + w_n f(x_n)
holds exactly for every polynomial f of degree at most 2n - 1.
Given alpha, beta and n, output the rule.
One line with alpha, beta (each with at most 6 digits after the decimal point) and the integer n.
n lines. Line i contains x_i and w_i, nodes in increasing order, each with absolute error at most 1e-10 or relative error at most 1e-7.
0 <= alpha <= 5
1.1 <= beta <= 4
1 <= n <= 20
This is a standard problem: a submission scores full points if it produces the correct output for every test case, and zero otherwise.
Numeric answers are accepted if they are within an absolute tolerance of 1e-10 or a relative tolerance of 1e-07 of the expected value.
1.0 2.0 3
0.37813462343448623 0.18961964883835322 1.0862473525771112 0.27395311770345276 2.0268039148847183 0.03642723345819414
0.5 1.5 8
0.12723205095023052 0.08505413608252807 0.4866967115212445 0.23016724097900004 1.0435949028224707 0.22743946901103657 1.7745936676821876 0.10200616399291837 2.672710618598501 0.02036356714153065 3.7513302073279813 0.0015985159316827032 5.058914529912156 3.744544762342451e-05 6.746078310897918 1.2808034728544058e-07