Question

How do I generate a banded matrix in Python programming language? I need the function of code required to do this

Answer 1

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A matrix of given size is banded matrix where

bandedMatrix(i,j) = 0 , If (j < i-k1) or (j > i +k2), else put some number

here k1>=0 and k1 is lower bandwidth,

k2 >=0 and k2 is upper bandwidth. Maximum of k1 and k2 is called bandwidth of the matrix.

For example here we consider k1=k2.

So condition for banded matrix would be |i-j| > k

Please use below code:

#function to generate Banded matrix

def GenerateBandedMatrix(size,bandwidth):

    # Initialize the matrix of size*size

    matrix = [[0 for row in range(size)] for col in range(size)]

    count =1

    # iterate over matrix to create a banded matrix

    for i in range(size):

        for j in range(size):

            #if |i-j| > size then leave element of matrix as 0

            if(abs(i-j) > bandwidth):

                continue;

          

            # update the matrix with count and increase the count

            matrix[i][j] = count

            count +=1

          

    return matrix

# Driver code to call GenerateBandedMatrix

size =6

bandwidth =2

print('The banded Matrix is as below: ')

bandedMatrix = GenerateBandedMatrix(size,bandwidth)

#print the generated matrix

for i in range(size):

    for j in range(size):

        print(bandedMatrix[i][j], end ='')

        print(' ', end='')

    print('')

=============screen shot of the code ==================

Output: