# tests/testthat/test-dcnb.R In cnbdistr: Conditional Negative Binomial Distribution

```context("dcnb")

test_that("dcnb stops when it should", {

expect_error( dcnb(2000, 120, 90, 0.994) ) # missing an argument
expect_error( dcnb(-980, 2000, 120, 90, 0.994) ) # x < 0
expect_error( dcnb(2980, 2000, 120, 90, 0.994) ) # x > D
expect_error( dcnb(980, -2000, 120, 90, 0.994) ) # D < 0
expect_error( dcnb(980, 2000, -120, 90, 0.994) ) # r1 < 0
expect_error( dcnb(980, 2000, 120, -90, 0.994) ) # r2 < 0
expect_error( dcnb(980, 2000, 120, 90, -0.994) ) # lambda < 0

})

test_that("dcnb computes correctly", {

# lamba == 1
D <- 32
r1 <- 600
r2 <- 499
lambda <- 1
expect_equal(dcnb(0:D, D, r1, r2, lambda),  rmutil::dbetabinom(0:D, D, r1/(r1+r2), r1+r2))

# lambda < 1
D <- 64
r1 <- 563
r2 <- 49
lambda <- 0.72
tmp <- log(dcnb(0:D, D, r1, r2, lambda)) - log(rmutil::dbetabinom(0:D, D, r1/(r1+r2), r1+r2)) - c(0:D)*log(lambda)
expect_true(diff(range(tmp)) < 1e-11)

# lambda > 1
D <- 99
r1 <- 60
r2 <- 588
lambda <- 1.32
expect_equal(dcnb(0:D, D, r1, r2, lambda), dcnb(D:0, D, r2, r1, 1/lambda))

})
```

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cnbdistr documentation built on July 17, 2017, 5:02 p.m.