parabolaSlopes

0th

Percentile

Estimate the slope of an interpolating function using a parabola

Returns estimates of the slope of an interpolating function that runs through a set of points in the xy-plane.

Keywords
ts, smooth, math
Usage
parabolaSlopes(x,y)
Arguments
x,y

coordinates of points defining the interpolating function.

Value

Returns an estimate of the slope of the interpolant at (x,y).

Note

This function is used as part of the Stineman interpolation function stinterp. It is rarely called directly by the user, and checking of x and y must be performed by the calling function.

The parabola method provides a better approximation of the slope for smooth functions than the original method suggested by Stineman (1980), which is provided by the function stinemanSlopes (see the documentation of the function stinterp for further information), but it results in higher slopes near abrupt steps or spikes and can lead to some overshooting where Stineman's method does not.

See Also

stinterp and stinemanSlopes.

Aliases
  • parabolaSlopes
Examples
# NOT RUN {
x <- seq(0,2*pi,by=pi/6)
y <- sin(x)
# }
# NOT RUN {
parabolaSlopes(x,y)
# }
Documentation reproduced from package stinepack, version 1.3, License: GPL-2

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