0Using the Math Library in Python.
Python provides many useful mathematical functions in a special math library. A library is a module that contains some useful definitions. We now consider writing a program which illustrates the use of this library.
Task.
To compute the roots of a quadratic equation.
Now, as many of the students know, A Quadratic Equation has the form:
X = -b±(√b*b – 4 * a * c) / 2 * a
For any value of x, such an equation has two solutions. Now, let us write a Python program which will find out the two solutions. The input to the program will be the values of the coefficients a,b and c. and, the output will be the two solutions, or values.
import os
import math ## importing the math module
a = input("Please enter the coefficient a ")
b = input("Please enter the coefficient b ")
c = input("Please enter the coefficient c ")
a = int(a)
b = int(b)
c = int(c)
discRoot = math.sqrt(b*b - 4 * a * c)
root1 = (-b+discRoot) / (2 * a)
root2 = (-b-discRoot) / (2 * a)
print("Solutions are = ",root1,root2)
Result
Please enter the coefficient a 3
Please enter the coefficient b 4
Please enter the coefficient c -2
Solutions are = 0.38742588672279316 -1.7207592200561266
The student must remember that this program only works when b*b – 4 * a * c is > 0,since sqrt function does not work on negative numbers.!!! The user must trap this error in order to make the program run smoothly.
Thus, we have seen the use of the math library, the first place to look in case we need a mathematical function. The following table shows some other functions available in the math library.
Python Mathematics English
pi p An approximation of pi.
e e An approximation of e.
sin(x) sinx The sine of x.
cos(x) cosx The cosine of x.
tan(x) tanx The tangent of x.
asin(x) arcsinx The inverse of sine x.
acos(x) arccosx The inverse of cosine x.
atan(x) arctanx The inverse of tangent x.
log(x) lnx The natural (base e) logarithm of x
log10(x) log10 x The common (base 10) logarithm of x.
exp(x) e^x The exponential of x
ceil(x) ┌x┐ The smallest whole number >= x
floor(x) └x┘ The largest whole number <= x
