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Monte-Carlo Permutation Testing

Near the end of my first statistics class, I was introduced to the concept of a hypothesis test: given two sample sets, determine the probability that they were drawn from the same population. If this is less than your desired p-value (typically 5% or less, depending on your field), you can reject the [null-hypothesis][1] and accept the alternative hypothesis that the two samples are indeed from different populations.

This was presented to me in the context of social sciences, but it comes up in

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Random Sampling Without Replacement

Last time we talked about rolling unbiased virtural dice, now let's turn to opening virtual booster packs in a collectible card game. If you're a nerd like me, you may be interested in reading about the specifics of how cards are distributed in [Magic: The Gathering][2] and [Yu-Gi-Oh!][3], but our main concern here is to randomly select n items from an array of N options. I'm told that it's also useful in scientific computing or whatever.

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Unbiased Range Reduction of Pseudo-Random Numbers

Suppose you're working on a virtual board game and want to simulate the roll of a die. The first programming book I ever owned suggested the following:

int result = rand() % 6;

If you've spent any time reading about random numbers in computer science, you've probably heard that this is a bad idea. The reason that's usually given is that rand() (just like the standard RNGs of many other languages, such as

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/*******************************************************************************
Author: Tristan Dannenberg
Notice: No warranty is offered or implied; use this code at your own risk.
********************************************************************************
Approximate algorithm for generating length-limited prefix codes.

I came up with this idea while working on an animation of Huffman's algorithm,
and had a convincing informal argument for it being optimal.

Comparison with Package/Merge shows this to be false for heavily skewed symbol

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Crafting a Compiler from Scratch: Implementation Notes

For the past two weeks or so, I've been working on a little compiler project in C, mostly for educational purposes, i.e. to understand how a compiler really works. I'm not using any libraries, other than the C runtime library.

Introduction

I have a hand-written lexer and parser, and a simple code generator targetting

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// ...

static int32_t*
get_indentation_marks(Application_Links *app, Partition *part, Buffer_Summary *buffer, Cpp_Token_Array tokens, int32_t line_start, int32_t line_end, bool32 exact_align, int32_t tab_width){
    int32_t indent_mark_count = line_end - line_start;
    int32_t *indent_marks = push_array(part, int32_t, indent_mark_count);
    // Shift the array so line_index works correctly.
    indent_marks -= line_start;
    
    // NOTE: TLD modifications begin here