b2slope {richards} | R Documentation |
Finds the slope at x50
of a Richards curve,
or the parameter b
of a Richards curve with a given slope.
x2c
is for finding the parameters C
and E
from x50
.
b2slope(ny = X[, "ny"], b = X[, "b"], a = X[, "a"], d = X[, "d"], X = NULL, fold = 2, delta = 1e-09) slope2b(ny = X[, "ny"], slope = X[, "slope"], a = X[, "a"], d = X[, "d"], X = NULL, fold = 2, delta = 1e-09) ny2f(ny, delta = 1e-09) x2c(x50 = X[, "x50"], ny = X[, "ny"], b = X[, "b"], X = NULL, fold = 2, x50f = 1, delta = 1e-09)
ny |
the shape parameter: affects near which asymptote maximum 'growth' occurs. |
b |
a numeric scale parameter on the input axis,
the 'growth rate', the reciprocal of the scale parameter
scal for the four point logistic curve by SSfpl.
(The 'growth' parameter b should be negative, and a
is thus the right side (larger) asymptote, for Bertalenffy growth models.)
|
slope |
a numeric parameter representing the slope at
x50 of the curve. |
a |
a numeric parameter representing the horizontal asymptote on the
left side (very small values of input) for b positive,
else the horizontal asymptote on the right side. |
d |
a numeric parameter representing the horizontal asymptote on the
right side (very large values of input) for b positive,
else the horizontal asymptote on the left side. |
x50 |
a numeric parameter representing the input value at
the center of the curve:
The value of SSrichards will be
midway between a and d at x50 . |
x50f |
a numeric value, factor for x50 . |
X |
a numeric matrix with the parameters of the Richards curves. |
fold |
a numeric with the base of the logarithm. |
delta |
a numeric value.
If abs(ny) < delta then the Gompertz curve is used. |
The slope (with respect to the logarithm with base fold
of x
)
of the Richards curve is b * (d-a) * f * log(fold)
,
with f
given by ny2f
.
A numeric vector
Jens Henrik Badsberg