Homework, Material, and Software Manual for Math 4610
Routine Name: subtractMatrix
Author: Tanner Wheeler
Language: Python. This code can be run on a python 3 compiler. The file can be imported and then the method will run.
Description/Purpose: This method will subtract two matrices from each other that have the same dimensions mxn.
Input: The two inputs will be two two dimensional arrays of dimensions mxn. The second input will be subtracted from the first input.
Output: The output will be a new two dimensional array that is the subtraction of the two input arrays. The method will return an error if the arrays aren’t the same dimensions.
Usage/Example:
First let’s create two matrices a and b whose dimensions are 3x2 and set there values.
n = 2
m = 3
a = [[float(0)] * n for i in range(0,m)]
b = [[float(0)] * n for i in range(0,m)]
a[0][0] = float(1)
a[0][1] = float(8)
a[1][0] = float(4)
a[1][1] = float(4)
a[2][0] = float(5)
a[2][1] = float(6)
b[0][0] = float(3)
b[0][1] = float(1)
b[1][0] = float(1)
b[1][1] = float(0)
b[2][0] = float(3)
b[2][1] = float(2)
Now we have
a = [[1.0, 8.0],
[4.0, 4.0],
[5.0, 6.0]]
b = [[3.0, 1.0],
[1.0, 0.0],
[3.0, 2.0]]
Let’s print the output of our method given the matrices.
print(subtractMatrix(a, b))
This prints
[[-2.0, 7.0], [3.0, 4.0], [2.0, 4.0]]
to the console.
Implementation/Code: The following is the code for subtractMatrix(x, y)
def subtractMatrix(x, y):
if len(x) != len(y):
return "Error Invalid sizes!"
if len(x) != len(y):
return "Error Invalid sizes!"
z = [[0] * len(x[1]) for i in range(0,len(x))]
for i in range(0, len(x)):
for j in range(0, len(x[i])):
z[i][j] = x[i][j] - y[i][j]
return z
Last Modified: December 2018