Calculate Polynomials from Zeros or Values
Calculate either the monic polynomial with specified zeros, or the Lagrange interpolation polynomial through the (x,y) points.
poly.calc(x, y, tol=sqrt(.Machine$double.eps), lab=dimnames(y)[[2]])
x |
numeric vector specifying either the zeros of the desired polynomial if this is the only non-missing argument, or the x-values for Lagrange interpolation. |
y |
numeric vector or matrix specifying the y-values for the
Lagrange interpolation polynomial. If |
tol |
An absolute value tolerance, below which coefficients are treated as zero. |
lab |
If |
If y
is a matrix, the result is a list of polynomials using
each column separately.
If x
only is given, repeated zeros are allowed. If x
and y
are given, repeated values in the x
vector must
have identical y
values associated with them (up to
tol
), otherwise the first y-value only is used and a warning
is issued.
Either a polynomial object, or a list of polynomials, as appropriate.
In the latter case the object is of class "polylist"
.
poly.calc(rep(1,3)) ## -1 + 3*x - 3*x^2 + x^3 poly.calc(0:4, (0:4)^2 + 1) ## 1 + x^2 poly.calc(0:4, cbind(0:4, (0:4)^2 + 1), lab = letters[1:2]) ## List of polynomials: ## $a: ## x ## ## $b: ## 1 + x^2
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