amod {BIOdry}

Allometric scaling.

Description

Allometric models and parameters are used to scale organic growth.

Usage

amod(x, mp = c(1, 1), fun = y ~ a * (x^b))

Arguments

x

numeric vector.

mp

numeric. Allometric parameters. Default c(1,1) (see details).

fun

formula. Allometric model. To properly specify other formulas, the variables (e.g. x and y) should belong to letters[20:26].

Details

. Allometric models are useful to scale size-components of organisms such as tree diameters (mp = c(2,1)) and basal areas (mp = c(0.25 * pi,2)). Several parameter groups (c(a1,b1,a2,b2, ..., an,bn)) can be recursively processed. This enables computation of complex organic variables. For example, above-ground tree biomass could be computed from two parameter groups for tree-biomass, and over-bark diameter scaling.

Value

data.frame of the scaled variable (x) and relative increments (csx). These are computed with setdiff function.

Author(s)

Wilson Lara <[e-mail]>, Felipe Bravo <[e-mail]>

Examples

## Simulating TRW records:
set.seed(1)
trw <- ts(abs(rnorm(12,1,1)),start = 1950)
## Cumulative TRW:
cri <- cumsum(trw)
## tree diameters
td <- amod(cri,mp = c(2,1))
## plot of the tree diameters and the
## relative increments:
plot(ts(td))