Monthly Archives: July 2014

Skip Cramer’s Rule and just do Helzer’s Matrix Divide in J

In the last post,  we demonstrated the use of Cramer’s Rule as explained by Michael Kelley in Algebra Chapter 9.  We saw that Cramer’s Rule works in J, but in this post and in a previous post using  Matrix Divide … Continue reading

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Matrix division and Cramer’s Rule

In this post, we will demonstrate how you can apply Cramer’s Rule in J,  using  a sample problem in Michael Kelley’s  in his Algebra, pg. 126  Chapter 9. The original system of equations:                … Continue reading

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R.I.P. passengers MH-17

My heart goes out to the families who lost loved ones in the shoot down of the Malaysian Air Lines civilian airliner over the Ukraine.  I feel rage at the malevolence of some and the fecklessness of others who contributed … Continue reading

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Matrix Division made simple

The following might be a somewhat advanced topic for some of you.  But, don’t be intimidated, I actually think you’ll get it.   Gary Helzer wrote An Encyclopedia of APL for I-APL Limited,  which was part of British APL.  Dr. … Continue reading

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The Shape Command in J with Squares and Roots

Previously, I mentioned that W. Michael Kelley in his Algebra Book suggested you should memorize the first fifteen perfect squares.  Then, in his Pre-Algebra book on pg 278, he suggests you memorize the first twenty square roots.  I’ve never really … Continue reading

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Is your personality Type A or Type B?

I remember this idea as a big deal in psychology quite a few years back.  Two doctors in the 1950’s — Meyer Friedman and Ray Rosenman — said there were psychological and personality traits that doubled the risk of heart … Continue reading

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Earthquakes in Oklahoma today

More than seven minor earthquakes struck Oklahoma early Sunday morning.  The Seismograph measurements ranged from 2.6 to 2.9.  The early earthquakes were within 45 miles north of downtown Oklahoma City, along Interstate 35. Earthquakes are not unheard of in Oklahoma, … Continue reading

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Today a 6.8 Earthquake and Tsunami struck near Fukushima, Japan.

Another 6.8 Earthquake struck Fukushima, Japan this morning.  This is in the same area as the earthquake that struck the nuclear power plant in April 2011.  This latest earthquake was reported here and elsewhere.  The USGS summary is here. Update … Continue reading

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What a 9.2 Earthquake and Tsunami look like

According to Cal Tech, the earthquake (revised upward to 9.2)  and tsunami off the coast of Banda Aech, Sumatra, Indonesia, that took place December 25-26, 2004,  was the third largest earthquake ever recorded on a seismograph.  The earthquake occurred 19 … Continue reading

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Dogs and Learning: a followup to Cats and Learning

Last year, or more specifically, October 21, 2013,  I wrote a post titled “Cats and Learning,”   here’s the link.  It featured a video by Matt Hirst of his cat and dog trying to make a jail break through a … Continue reading

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