Official website: www.python.org
Latest version: 3.4 (at the time of this blog entry)
My mathematical notes on Python so far:
This is from the 3.4 instructions but should hold in the 2.7 version as well. I am trying to find a good iOS app to do this.
* A good suggestion is to watch a few tutorial YouTube videos on Python. Onestopprogramming has a good set of tutorials. Python is capable of doing many things, including working with computer files, my focus will be on some of the mathematical capabilities of Python.
* The uses of the equals symbol ( = ) in Python:
(1) A single equal sign means assignment.
x = 4 stores "4" in the variable x.
str = "Eddie" or str = 'Eddie' stores "Eddie" in the variable str.
(2) Two equals signs mean comparison, does x equal y? ( x = y ?)
12==12 returns True
(3) An exclamation mark in front of an equals sign means the comparison, does x not equal y? ( x ≠ y ?)
12!=12 returns False
* Variables that are assigned are defaulted to strings. In order to use variables to represent numbers, we must first declare them as such. The declarations are:
int: integer
long: long integer
float: floating numbers
complex: complex numbers
Example: float(x) declares x as a floating variable.
* Working with floating numbers can bring "weird results" due to Python internally representing every number as a binary representation (0s and 1s). For example,
2.2 * 2 returns 4.40000000000000004
Although the PC version returns 4.4. So this may just be he iOS or a not so good app I was using a the time (Python 3.3 iOS app).
In order to get this answer in more acceptable form. This requires the format declaration. It's syntax is generally this:
"{:.xf}".format(answer, expression, variable, etc..)
Where x is the number of decimal places desired.
Back to our example, let's express 2.2 * 2 using four decimal places:
"{:.4f}".format(2.2*2) returns '4.4000'
* To access mathematical functions beyond arithmetic, we must first import the math library. This is done usually at the beginning of each script (program).
Syntax: import math
Common math functions are what you would expect:
math.ceil(x): ceiling
math.fabs(x): absolute value
math.factorial(x): factorial of x, integers only
math.gamma(x): the gamma function, Γ(x)
math.erf(x): error function
math.fsum(list): sum of a lists elements (in single square brackets)
math.exp(x): e^x
math.log(x, base): logarithm. Leave base out for natural logarithms ( ln x ).
math.pow(x, y): x^y. More expansive than using the double asterisk. ( x ** y )
math.sqrt(x): √x
math.sin(x), math.cos(x), math,tan(x): sine, cosine, and tangent, respectively. The angle is always in radians.
math.asin(x), math.acos(x), math.atan(x): arcsine, arccosine, and arctangent, respectively. The angle returned is in radians.
There are hyperbolic versions of these functions.
math.degrees(x): convert from radians to degrees
math.radians(x): convert from degrees to radians
math.pi: π
math.e: e
A complete list can be found in the python documentary.
* Quick math symbols that don't need the math library to be imported:
Arithmetic functions: +, , *, and /. (For those new to programming, * represents × and / represents ÷)
Power: ** (two asterisks)
Modoluo: %
Representing exponential powers of 10: e+N or eN
That is my quick notes for now. I want to post some programs using the Python language in the upcoming weeks.
Eddie
A blog is that is all about mathematics and calculators, two of my passions in life.
Monday, July 21, 2014
My Mathematical Notes for Python (so far)
Subscribe to:
Post Comments (Atom)
Retro Review: TI95 Procalc
Retro Review: TI95 Procalc This review covers the calculator itself, not any of the optional accessories which includes a ...

Casio fx991EX Classwiz Review Casio FX991EX The next incarnation of the fx991 line of Casio calculators is the fx991 EX. ...

The Odds of Hitting it Big The number of possible combinations is fairly easy to calculate. You multiply the number symbols each slot has ...

Over the next month, maybe month and a half, I plan to post programming tutorials for the HP (Hewlett Packard) Prime. If you have program...
No comments:
Post a Comment