Computer science: what is a hash function?

Tutoring computer science, you might be asked about hash functions. The tutor shares an idea about them.

hash function:a mapping of a large data set to a much smaller one that preserves a desired peculiarity of the original data. The input data may be of complex type such as objects, while the output may be a string or a set of integers (or, possibly, just a single integer).
An example of a hash function might be as follows: Suppose a restaurant’s reservations for tonight are five tables of four, ten of two, and a large party of eight. Describing that as reservations for 48, you’ve used a hash function.

Source:

cs.stackexchange.com

Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.

Home computer use, English: bookmarks

Home computer use can lead to constant self-tutoring. The tutor reflects about bookmarks.

In The Road Not Taken, Robert Frost arrives at a fork where he must pick one road to travel. Looking down each as far as he can, he chooses the second. He then confides to the reader,

Oh, I kept the first for another day!
Yet knowing how way leads on to way,
I doubted if I should ever come back.

An internet researcher faces much the same situation: one site can lead to another, then more may link from it. You might even visit a page but not read much of it, only to save it as a bookmark “for another day” – knowing, just like Frost intimates, that you’ll unlikely return.

Today I began looking through the bookmarks that I’ve accumulated on the main computer. I rediscover so many links to great sites that I recall finding, but didn’t follow up. Time is limited, and the topic that was urgent that day soon gave way to another.

On the internet, we’ve all joined the company of Robert Frost in a way perhaps unimaginable when he wrote The Road Not Taken circa 1915. With so many pages acting as nodes to groups of others, the internet surfer faces choice after choice, leaving by far most pages – and the ones that would follow – unexplored.

Source:

Smith, Philip (editor). 100 Best-Loved Poems. New York: Dover Publications, Inc, 1995.

www.poets.org

Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.

Calculator usage: changing angle mode on the Media SC-1000

Tutoring math, scientific calculators are always interesting. The tutor mentions changing between DEG and RAD mode on the Media SC-1000.

The Media SC-1000 is an appealing scientific calculator. I’ve been using it often during my sessions lately, having bought one years ago.

To move into RAD mode from DEGREE mode (or back the other way), do the following:

  1. Press the MODE CLR button twice, at which time you’ll hopefully see the choice for Deg, Rad, or Gra.
  2. Select which of Deg, Rad, or Gra you wish.

HTH:)

Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.

Math: counting: how many ways can four whole numbers sum to 10?

Tutoring math, you might be asked counting problems. The tutor brings up one.

How many solutions can be found to x1 + x2 + x3 + x4 = 10, where x1, x2, x3, and x4 are all whole numbers?

Imagine three pipes |||, and ten asterisks **********. Then 5, for example, appears as *****. The pipes separate the values of x1, x2, x3, and x4. Therefore, the solution x1=3, x2 =0,x3=5, x4=2 shows as

***||*****|**

By the guidelines above, any solution to x1 + x2 + x3 + x4 = 10 can be shown as a sequence of 13 characters: three pipes and ten asterisks. The variability is which three positions the pipes occupy. 13C3 is how many ways the pipes can be distributed. Therefore, there are 13C3 solutions to x1 + x2 + x3 + x4 = 10, where x1, x2, x3, and x4 are all whole numbers.

Source:

Ross, Sheldon. A First Course in Probability. New York: Macmillan Publishing Company, 1988.

Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.

English, Military terminology: radar is an acronym

Reading leads to more self-tutoring: the tutor reveals what he just learned: radar is an acronym.

RADAR: RAdio Detection And Ranging

In this context, ranging apparently means determining the detected object’s range, or distance away.

Source:

Mish, Frederick C. (editor). The Merriam-Webster Dictionary. Springfield: Merriam-Webster, 2004.

www.abbreviations.com

Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.

English: what does picayune mean?

Tutoring English, new vocabulary is always interesting. The tutor brings up the word picayune.

picayune(adj): not worth consideration.

The chef measured a teaspoon of salt from her palm, asserting the difference between it and that from a measuring spoon to be picayune.

Source:

Barber, Katherine et al. Oxford Canadian Dictionary of Current English. Don Mills: Oxford University Press, 2005.

Mish, Frederick C. (editor). The Merriam-Webster Dictionary. Springfield: Merriam-Webster, 2004.

Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.

Lifestyle: Christmas spirit: decorating wild trees

Even the Christmas spirit can involve self-tutoring. The tutor shares a trend he appreciates.

I recall seeing, along the Inland Island Highway, trees hung with Christmas ornaments. The trees seemed “in the middle of nowhere”, yet someone had adorned them for Christmas.

To me, making the effort to decorate a wild tree shows a higher level of Christmas spirit. The decorators may never see the adorned tree again, but share their festivity with whoever happens to behold it.

Seeing decorated trees out in nature, far away from settlement, reinforces another idea as well – that God is everywhere. Moreover, people who appreciate God seek and celebrate Her/Him in places you might not imagine.

Last Friday I saw this outdoor tree decorated for Christmas; I’m happy to share it, and its meaning.

Whichever faith you may be, Happy Holidays. I’ll repeat it:)

Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.

Chemistry: disproportionation

Tutoring chemistry, you likely touch on redox. The tutor shows a disproportionation.

disproportionation: a reaction in which the same species both oxidizes and reduces.

Example:

Cu+ → Cu2+ + e E=-0.153
Cu+ + e → Cu(s) E=0.521

The above disproportionation, theoretically, is spontaneous, since the potentials (E) sum positive (0.368V in this case).

Source:

Mortimer, Charles E. Chemistry, 6th ed. Belmont: Wadsworth, 1986.

sites.chem.colostate.edu

Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.

Technology, mobile phones: Nexus 4: .aux folder in DCIM

Using technology can lead to continual self-tutoring. The tutor mentions a fact he learned today.

Looking to download some photos from my phone to storage, I found a .aux folder inside the DCIM one. (DCIM means Digital Camera IMages.)

Wondering what the .aux folder contains, I opened it and found a single image relating to many others the kids took years ago while assembling an animation. Yet, why is it there, alone?

I discovered a similar photo to it in the main DCIM, alongside the others from that day. Yet, it’s from a few days later. It’s a mirror image of the one in .aux.

Apparently, when an image is altered, its original may (on some platforms) be stored in a .aux folder, while the changed one replaces its predecessor in DCIM. Such seems to be what happened in this case, anyway.

HTH:)

Source:

www.howtogeek.com

android.stackexchange.com

www.reddit.com

Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.

English: the adverb lukewarmly

Tutoring English, new words are great discoveries. The tutor shares his discovery of lukewarmly.

Commonly known, lukewarm is an adjective that means somewhat warm – perhaps a little above room temperature.

Today I’ve discovered the related adverb, lukewarmly:

lukewarmly (adv): in a manner showing lack of enthusiasm.

The audience received the play lukewarmly.

Source:

Mish, Frederick C. The Merriam-Webster Dictionary. Springfield: Merriam-Webster, 2004.

Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.