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A first order separable ordinary differential equation is (arguably) the easiest type of differential equation to solve, and takes the form of
$$N(y)\frac{dy}{dx} = M(x) \\
y(x_0) = y_0$$
For two given functions \$N(y)\$ and \$M(x)\$ and an initial condition \$y(x_0) = y_0\$.
Your task is to ...
Explicit-ify APL expressions involving trains code-golf parsing apl
Related: Clearly parenthesize APL trains
Background
In the most basic form, APL has two kinds of tokens: arrays and functions. For this challenge, we will use a lowercase alphabet a-z for an array, and an uppercase alphabet A-...
The Double-Castle Numbers™ code-golfnumberbase-conversion
Introduction
A double-castle number™ is a positive integer number that has a pattern of $$\underbrace{a\cdots a}_{m\text{ }a\text{s}}b\underbrace{a\cdots a}_{m\text{ }a\text{s}}b\underbrace{a\cdots a}_{m\text{ }a\text{s}}\underbrace{a\cd...0
Self-distances completion
Let \$A\$ be a \$k\$ -permutation of \$n\$ containing \$n\$ (with \$n,k\ge2\$ )
$$
A = (a_1,\dots,a_k)\quad n\in A
$$
The self-distances completion of \$A\$ it's performed recursively as follow:
Starting from \$i=2\$, while \$a_i\in A:\$
If \$d=|a_i-a_{i-1}|\$ is not...
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Self-distances completion - Minimum k to get them all
Let \$\mathcal{A}_{n,k}\$ be the set of all \$k\$ -permutation of \$n\$ containing \$n\$ (with \$n,k\ge2\$ )
$$
A\in \mathcal{A}_{n,k}\quad A = (a_1,\dots,a_k)\quad n\in A
$$
The self-distances completion of \$A\$ it's performed recursively a...
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The riddle
In yesterday's newspaper, I found a riddle in which a Rook should start in the lower left corner of a 12x12 checkerboard and then, during a round trip, visit each field but certain ones exactly once. The riddle came with a picture that helped to clarify which fields to spare out durin...
I want to reconstruct a table of contents using the package stringr in R to capture the pattern of all headlines. The raw headlines look like this:
r\nPart I The Federal Government’s objectives and priorities in the area\r\n of research and innovation policy ...
