Three on Thursday

Joining Carole and friends for Three on Thursday, today with three things about pi. Today is Pi Day 3/14, and even if you don't care about it mathematically, it's a great reason to eat pie. While you're having a slice (apple, cherry, peach or pizza), consider these three things.

• Pi is the ratio of a circle's circumference to its diameter, or

         This isn't exactly exciting, but if you consider that this ratio is a constant, whatever the size of the circle, that is a little more                            interesting. The usual approximation for pi is 3.14159.

• Pi is also an irrational number. In math, that means it can't be written as the ratio of two integers, and it has an infinite number of digits.

• What the heck is it used for? Well, NASA uses it to calculate trajectories, determine the size of craters, and figure out the volume of fuel tanks and see out how much propellant a spacecraft has. Another important practical application is in signal processing. A fundamental operation here is the Fourier transform, which converts a signal to a frequency spectrum. Your cell phone does a Fourier transform when it communicates with the local cell tower.

My favorite mathematician (Ryan) thinks that we should really be celebrating e, a mathematical constant that is the base of the natural logarithm (the unique number whose natural logarithm is equal to one). Its approximation is 2.71828, so I suppose it could be celebrated on February 7th in the US, but without something delicious to eat associated with it, it's never going to measure up to Pi(e) Day. 

Head on over to Carole's for more Three on Thursday thoughts.