在R包移相器中绘制ODE相位差时出错

我试图用phaseR软件包在R中绘制一幅二维相位图。这是我想做的一个例子：

有效的例子

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我不明白为什么向量不显示，或者为什么蓝色的nullcline缺失

从数学上讲，x.lim范围超出了函数可以有值的域。因为dy[2]表达式的一个项的分母中有x，所以函数在

x==0

处爆炸，然后在函数代码内部的

dy[]

-矩阵中会出现NA。（有点含糊不清，因为您的

dy

-对象是一个2元素向量，而查看代码时，计算存储在名为

dx

和

dy

的二维矩阵中）

flowField#看看代码
png（）
沃尔普流场
library(phaseR)

lotkaVolterra <- function(t, y, parameters) {
x <- y[1]
y <- y[2]
lambda  <- parameters[1]
epsilon <- parameters[2]
eta     <- parameters[3]
delta   <- parameters[4]
dy    <- numeric(2)
dy[1] <- lambda*x - epsilon*x*y
dy[2] <- eta*x*y - delta*y
list(dy)
}

lotkaVolterra.flowField <- flowField(lotkaVolterra, x.lim = c(0, 5), y.lim = c(0, 10), parameters = c(2, 1, 3, 2), points = 19, add = FALSE)

grid()


lotkaVolterra.nullclines <- nullclines(lotkaVolterra, x.lim = c(-1, 5), y.lim = c(-1, 10), parameters = c(2, 1, 3, 2), points = 500)

y0 <- matrix(c(1, 2, 2, 2, 3, 4), ncol = 2, nrow = 3, byrow = TRUE)

lotkaVolterra.trajectory <- trajectory(lotkaVolterra, y0 = y0, t.end = 10, parameters = c(2, 1, 3, 2), colour = rep("black", 3))

WalpeFun <- function(t, y, parameters) {
  x <- y[1]
  y <- y[2]
  k <- parameters[1]
  z <- parameters[2]
  w <- parameters[3]
  b <- parameters[4]
  d <- parameters[5]
  v <- parameters[6]
  a <- parameters[7]
  g <- parameters[8]
  l <- parameters[9]
  e <- parameters[10]
  dy <- numeric(2)
  dy[1] <- 2.5*(1-(x/k)^z)+g*l+w*e - b*(x*y/d^2+y^2)
  dy[2] <- 2.5 * (1 - (y/x + v)^a)
  list(dy)
}


Walpe.flowField <-flowField(WalpeFun, x.lim = c(0, 150), y.lim = c(-1, 50), parameters = c(120.73851, 0.51786, -0.75178, 0.00100, 1.00000, 500, 0.001, 0.01102, 320.995455, 5.582273) , points = 20, add = FALSE)

grid()

Walpe.nullclines <-nullclines(WalpeFun, x.lim = c(0, 150), y.lim = c(-1, 50), parameters = c(120.73851, 0.51786, -0.75178, 0.00100, 1.00000, 500, 0.001, 0.01102, 320.995455, 5.582273))

y0 <- matrix(c(8.2, 2), ncol = 2, nrow = 1, byrow = TRUE)

Walpe.trajectory <-trajectory(WalpeFun, y0 = y0, t.end = 100, parameters = c(120.73851, 0.51786, -0.75178, 0.00100, 1.00000, 500, 0.001, 0.01102, 320.995455, 5.582273),system = "two.dim", colour = "black")

Error in if ((dx[i, j] != 0) & (dy[i, j] != 0)) { : missing value where TRUE/FALSE needed

flowField  #look at the code
png()
Walpe.flowField <-flowField(WalpeFun, x.lim = c(0.01, 150), y.lim = c(-1, 50), parameters = c(120.73851, 0.51786, -0.75178, 0.00100, 1.00000, 500, 0.001, 0.01102, 320.995455, 5.582273) , points = 20, add = FALSE, system="two.dim")
Walpe.nullclines <-nullclines(WalpeFun, x.lim = c(0.01, 150), y.lim = c(-1, 50), parameters = c(120.73851, 0.51786, -0.75178, 0.00100, 1.00000, 500, 0.001, 0.01102, 320.995455, 5.582273))

y0 <- matrix(c(8.2, 2), ncol = 2, nrow = 1, byrow = TRUE)

Walpe.trajectory <-trajectory(WalpeFun, y0 = y0, t.end = 100, parameters = c(120.73851, 0.51786, -0.75178, 0.00100, 1.00000, 500, 0.001, 0.01102, 320.995455, 5.582273),system = "two.dim", colour = "black")
dev.off()