Description Usage Arguments Value Examples
This function calculates the gradient field.
1 | VecDecomGrad(surface)
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surface |
matrix output from |
returns an array of the gradient vector field. The array has three dimensions with the respective lengths of the columns of the surface, the rows of the sruface, and the number of variables (always 2). The two variables are the x-negative gradient of the quasi-potential surface and the y-negative gradient of the quasi-potential surface.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 | # First, the system of equations
equationx <- "1.54*x*(1.0-(x/10.14)) - (y*x*x)/(1.0+x*x)"
equationy <- "((0.476*x*x*y)/(1+x*x)) - 0.112590*y*y"
# Second, shared parameters for each quasi-potential run
xbounds <- c(-0.5, 10.0)
ybounds <- c(-0.5, 10.0)
xstepnumber <- 100
ystepnumber <- 100
# Third, first local quasi-potential run
xinit1 <- 1.40491
yinit1 <- 2.80808
storage.eq1 <- QPotential(x.rhs = equationx, x.start = xinit1,
x.bound = xbounds, x.num.steps = xstepnumber, y.rhs = equationy,
y.start = yinit1, y.bound = ybounds, y.num.steps = ystepnumber)
# Fourth, second local quasi-potential run
xinit2 <- 4.9040
yinit2 <- 4.06187
storage.eq2 <- QPotential(x.rhs = equationx, x.start = xinit2,
x.bound = xbounds, x.num.steps = xstepnumber, y.rhs = equationy,
y.start = yinit2, y.bound = ybounds, y.num.steps = ystepnumber)
# Fifth, determine global quasi-potential
unst.x <- c(0, 4.2008)
unst.y <- c(0, 4.0039)
ex1.global <- QPGlobal(local.surfaces = list(storage.eq1, storage.eq2),
unstable.eq.x = unst.x, unstable.eq.y = unst.y, x.bound = xbounds,
y.bound = ybounds)
# Sixth, creat the gradient vector field
VDG <- VecDecomGrad(surface = ex1.global)
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