---
title: "flexIC: Minimal, Runnable Demo"
author: "Kevin E. Wells, PhD"
date: "2025-06-26"
output: rmarkdown::html_vignette
vignette: >
  %\VignetteIndexEntry{flexIC demo}
  %\VignetteEngine{knitr::rmarkdown}
  %\VignetteEncoding{UTF-8}
---

```{r setup, include=FALSE}
knitr::opts_chunk$set(collapse = TRUE, comment = "#>")
library(flexIC)
library(mvtnorm)
library(microbenchmark)
set.seed(123)
```

## 1 Simulate marginals

```{r}
n <- 200; k <- 5
Sigma <- matrix(0.6, k, k); diag(Sigma) <- 1
X0  <- mvtnorm::rmvnorm(n, sigma = Sigma)
R_star <- cor(X0, method = "spearman")
```

## 2 IC vs flexIC

```{r}
out_ic   <- flexIC(X0, R_star, eps = "none")
out_flex <- flexIC(X0, R_star, eps = 0.02, max_iter = 50)
X_ic     <- out_ic
X_flex   <- out_flex
```

## 3 Maximum rank-error

```{r}
err_ic   <- max(abs(cor(X_ic  , method = "spearman") - R_star))
err_flex <- max(abs(cor(X_flex, method = "spearman") - R_star))

data.frame(
  method         = c("IC (eps = 'none')", "flexIC (eps = 0.02)"),
  max_rank_error = c(err_ic, err_flex)
)
```

## 4 Speed benchmark

```{r}
microbenchmark(
  IC     = flexIC(X0, R_star, eps = "none"),
  flexIC = flexIC(X0, R_star, eps = 0.02, max_iter = 50),
  times  = 100L
)
```

## 5 Optional: Visual check

```{r}
if (requireNamespace("ggplot2", quietly = TRUE)) {
  flexIC::plot_marginals_grid(X0, X_flex, bins = 30)
}
```

## 6 Session info

```{r}
sessionInfo()
```