test_document.Rmd

---
title: "This is a test."
date: "`r date()`"
author: "`r Sys.getenv('USERNAME')`"
---

```{r setup, include=FALSE}
library(knitr)
fig.dim <- 6
opts_chunk$set(fig.width=2*fig.dim,
               fig.height=fig.dim,
               fig.align='center')
```

The date today is `r date()`.
Here is a plot of a spiral.
```{r spiral_plot}
tt <- seq(0, 20*pi, length.out=400)
plot(1.01^seq_along(tt) * cos(tt), 1.01^seq_along(tt) * sin(tt), type='l')
```

Here we use Stan to infer the mean of an inverse Exponential.
```{r stan_block}
library(rstan)
stan_block <- "
data {
    int N;
    vector<lower=0>[N] x;
}
transformed data {
    vector[N] y;
    y = 1.0 ./ x;
}
parameters {
    real<lower=0> beta;
}
transformed parameters {
}
model {
    y ~ exponential(beta);
}
generated quantities {
}
"
fit <- stan(model_code=stan_block,
            data=list(x=1/rexp(100), N=100),
            chains=2, iter=1000)
summary(fit)
```