View source: R/plot_direction_Dopt.R

plot_direction_Dopt | R Documentation |

Verify the optimality condition for the D-optimal design

```
plot_direction_Dopt(u, design, tt, FUN, theta)
```

`u` |
The discretized design points. |

`design` |
The D-optimal design that contains the design points and the associated weights. |

`tt` |
The level of skewness. |

`FUN` |
The function to calculate the derivative of the given model. |

`theta` |
The parameter value of the model. |

This function produces the figure for the negative value of the directional derivative of the given D-optimal design of the compact supports. According to the general equivalence theorem, for an optimal design, all the directional derivative should be below zero line.

The plot of the negative value of the directional derivative of a D-optimal design

```
poly3 <- function(xi, theta){
matrix(c(1, xi, xi^2, xi^3), ncol = 1)
}
design = data.frame(location = c(-1, -0.447, 0.447, 1),
weight = rep(0.25, 4))
u = seq(-1, 1, length.out = 201)
plot_direction_Dopt(u, design, tt=0, FUN = poly3,
theta = rep(0, 4))
```

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