---
title: "flexIC: Minimal, Runnable Demo"
author: "Kevin E. Wells, PhD"
date: "`r Sys.Date()`"
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)      # raw data
R_star <- cor(X0, method = "spearman")         # target rank‑R
```

## 2 IC (m = 1) vs flexIC (m = 50)

```{r}
## 2  IC (m = 1) vs flexIC (m = 20)

out_ic   <- flexIC(X0, R_star, m = 1 ,  eps = 0   )   # classic IC
out_flex <- flexIC(X0, R_star, m = 20, eps = 0.02)   # flexIC

X_ic   <- out_ic[[1]]
X_flex <- out_flex[[1]]



if (is.null(dim(X_ic)))   X_ic   <- matrix(X_ic  , nrow = n, ncol = k)
if (is.null(dim(X_flex))) X_flex <- matrix(X_flex, nrow = n, ncol = k)
```

## 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 (m = 1)", "flexIC (m = 50)"),
  max_rank_error = c(err_ic, err_flex)
)
```

## 4 Speed benchmark

```{r}
microbenchmark(
  IC     = flexIC(X0, R_star, m = 1 ,  eps = 0   ),
  flex50 = flexIC(X0, R_star, m = 50, eps = 0.02),
  times  = 100L
)
```

## 5 Session info

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