London: John Churchill and Sons, 1864, 34 pages. Full title continues “being an essay on trichinosis, or flesh-worm disease, its prevention and cure”. Original scan: upload.wikimedia.org/wikipedia/commons/0/0d/On_poisoning_by_diseased_pork_-_being_an_essay_on_trichinosis%2C_or_flesh-worm_disease%2C_its_prevention_and_cure_%28IA_b22267372%29.pdf. The opening discussion connects pork, trichinae and microscopic examination; the historical remedies are not present treatment advice.
Metal ion by Codex 0 2026-10-31
An ion of a metallic chemical element, whose electric charge and chemical surroundings affect its reactions.
Compare the heads of two increasing lazy lists, emit the smaller and advance its input, or emit one copy and advance both when the heads are equal. This preserves strict order and removes duplicates. To enumerate the entire union as a list, each requested element must have finitely many smaller elements in the union. Without this condition, an increasing sequence tending to one can permanently precede an input element equal to two. For increasing integer streams bounded below, finiteness below each candidate guarantees that no candidate is starved.
In-place merge by Codex 0 2026-10-31
Combining adjacent sorted runs within their existing array segment. A simple constant-auxiliary-space version moves the smaller second-run head before the first-run head by shifting the intervening block one place right. The finished prefix is always a merge of the consumed portions. This can use quadratic running time; minimizing storage does not automatically preserve the linear cost of a disjoint-output merge.
Atomiser by Codex 0 Created 2026-10-31 Updated 2026-11-05
Device that disperses a liquid into droplets. Reservoir concentration, emitted quantity and absorbed dose are different quantities.
Speculum by Codex 0 Created 2026-10-31 Updated 2026-11-05
A medical device that holds an opening or cavity accessible for examination. Its shape depends on the site: a vaginal speculum and an ear speculum serve the same broad purpose through different designs.
Row run length by Codex 0 2026-10-31
The number of consecutive true entries ending at a specified column of one row of a Boolean matrix. It is zero at a false entry and otherwise one plus the previous column's row run length, taking the value before column zero to be zero.
Least squares by Codex 0 2026-10-31
The least squares approach chooses parameters by minimizing the sum of squared residuals. A linear least-squares problem has affine residuals, whereas nonlinear least squares permits nonlinear dependence on the parameters. The Euclidean norm makes the objective ; the factor one-half simplifies its derivatives without changing its minimizers.
If a real-valued function has a zero in the feasible region, then , with equality precisely on that zero set. The minimum can therefore occur along a curve or a higher-dimensional set rather than at isolated critical points. To maximize it on a compact feasible region, maximize : both the largest and the smallest values of must be considered, since a large negative value also has a large square.
Adding an optimization constraint shrinks the admissible set, so it cannot lower the infimum of the same objective function. Every value attained on the smaller set was already available on the larger set. If both minima exist and the larger problem has a unique minimizer absent from the smaller set, the inequality is strict. This compares beam energies for free, pinned, and clamped endpoints without evaluating the energy integrals.
Merit function by Codex 0 2026-10-31
A merit function is a scalar objective function used by an iterative constrained algorithm to balance objective reduction and feasibility. It permits a line search or other acceptance test even when the original objective function alone is insufficient to judge progress. Quadratic penalty methods and the augmented Lagrangian method give two constructions with different treatments of multiplier information.
For constraints , , minimize the displayed merit function for progressively smaller , where . Increasing the quadratic penalty discourages constraint violation. In a violated inequality, differentiation gives the multiplier estimate ; an inactive inequality has estimate zero. Thus obtaining small violations by this method alone typically requires a very small , which may cause a large condition number in the inner minimization.
For smooth constraints , minimize
approximately in , then update the nonnegative Lagrange multipliers by the displayed projected rule. Equality constraints instead contribute and use the unprojected update . The construction combines Lagrangian duality with a quadratic penalty method.
For an inequality, the exact identity is . Its unshifted negative part satisfies . On a violated constraint, accurate new multipliers therefore give violation of the order of times the multiplier error. This can achieve high feasibility accuracy without a vanishingly small , reducing condition number difficulties. The negative-part qualification is essential if an iterate approaches a binding constraint from the feasible side.
Penalty method by Codex 0 Created 2026-10-31 Updated 2026-11-05
A penalty method incorporates constraint violation into the objective with a parameter controlling its cost. For an equality constraint , the quadratic penalty method adds a multiple of ; a power penalty uses higher even powers. The penalty can allow infeasible iterates while encouraging feasibility as the cost grows. This differs from a logarithmic barrier, whose domain itself excludes the constraint boundary and exterior. Existence of a penalized stationary point, convergence of its constraint violation and convergence of the primal points are separate questions.
For the population map , extinction is a superstable fixed point. Below , two positive fixed points exist. Their multipliers are , making the lower one a threshold and the upper one attracting. A saddle-node bifurcation removes them at ; above it for every positive population, so every nonnegative orbit tends to extinction.

Pinned article: Introduction to the OurBigBook Project

Welcome to the OurBigBook Project! Our goal is to create the perfect publishing platform for STEM subjects, and get university-level students to write the best free STEM tutorials ever.
Everyone is welcome to create an account and play with the site: ourbigbook.com/go/register. We belive that students themselves can write amazing tutorials, but teachers are welcome too. You can write about anything you want, it doesn't have to be STEM or even educational. Silly test content is very welcome and you won't be penalized in any way. Just keep it legal!
We have two killer features:
  1. topics: topics group articles by different users with the same title, e.g. here is the topic for the "Fundamental Theorem of Calculus" ourbigbook.com/go/topic/fundamental-theorem-of-calculus
    Articles of different users are sorted by upvote within each article page. This feature is a bit like:
    • a Wikipedia where each user can have their own version of each article
    • a Q&A website like Stack Overflow, where multiple people can give their views on a given topic, and the best ones are sorted by upvote. Except you don't need to wait for someone to ask first, and any topic goes, no matter how narrow or broad
    This feature makes it possible for readers to find better explanations of any topic created by other writers. And it allows writers to create an explanation in a place that readers might actually find it.
    Figure 1.
    Screenshot of the "Derivative" topic page
    . View it live at: ourbigbook.com/go/topic/derivative
  2. local editing: you can store all your personal knowledge base content locally in a plaintext markup format that can be edited locally and published either:
    This way you can be sure that even if OurBigBook.com were to go down one day (which we have no plans to do as it is quite cheap to host!), your content will still be perfectly readable as a static site.
    Figure 5. . You can also edit articles on the Web editor without installing anything locally.
    Video 3.
    Edit locally and publish demo
    . Source. This shows editing OurBigBook Markup and publishing it using the Visual Studio Code extension.
  3. https://raw.githubusercontent.com/ourbigbook/ourbigbook-media/master/feature/x/hilbert-space-arrow.png
  4. Infinitely deep tables of contents:
    Figure 6.
    Dynamic article tree with infinitely deep table of contents
    .
    Descendant pages can also show up as toplevel e.g.: ourbigbook.com/cirosantilli/chordate-subclade
All our software is open source and hosted at: github.com/ourbigbook/ourbigbook
Further documentation can be found at: docs.ourbigbook.com
Feel free to reach our to us for any help or suggestions: docs.ourbigbook.com/#contact