Math: definition of closed
The tutor explains the concept of “closed” in math. If a set is closed under a certain operation, the result you get is still in the set. For instance, the even numbers are closed under addition: when you add two …
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The tutor explains the concept of “closed” in math. If a set is closed under a certain operation, the result you get is still in the set. For instance, the even numbers are closed under addition: when you add two …
Continuing about Pythagorean triples, the tutor considers the isosceles case. In my previous post I discussed all-integer solutions to the Pythagoras equation a^2 + b^2 =c^2 Such solutions are often called Pythagorean triples. Presently we consider the possibility of Pythagorean …
Math: Are there (integer) Pythagorean triples with two equal sides? Read more »
The tutor gives a few integer solutions to a2+b2=c2. All-integer solutions to a2+b2=c2 are called Pythagorean triples. They are comparativeley rare. Here are three sets I know: 3,4,5 5,12,13 8,15,17 From the sets above, infinitely more can be generated: multiplying …
The tutor comments on a New Year’s resolution that surprises him. Since before New Year’s, I’ve been asking people what their New Year’s resolution might be. Hardly anyone committed to one; what I remember is being told “I don’t make …
Lifestyle: New Year’s resolutions: getting organized? Read more »
The tutor continues with the part life example, this time offering a two-sided confidence interval. In my previous post I gave the premise of a part whose mean life (μ) is 36 months, with standard deviation (σ) 10 months. I …
Statistics: part life: a two-sided confidence interval Read more »
The tutor gives an example of a confidence interval. Example 1: Let’s imagine a part has mean lifetime thirty-six months, with standard deviation ten months. What minimum time will it last, with 95% confidence? Solution: Let’s use μ for mean, …
The tutor brings up another great find from the Windows Start menu. I’ve rediscovered the Windows 7 calculator. It can be opened by typing calc.exe into the search box (Start Menu), or else at the Command Prompt. It’s also available …
Windows 7: accessories: the calculator: standard deviation Read more »
The tutor mentions a helpful feature of CSS. Programmers are familiar with the idea of comments – code that the computer doesn’t process, but is meant for humans to read. Commenting is useful to explain what sections of code do. …
The tutor tells a useful hint he learned from unix.com. Sometimes, searching a directory in Linux, the results are so numerous that the user is plunged to the end, not being able to see the early or middle entries. There …