MATLAB: How to linearly change values in matrix

MATLABmatrixmatrix manipulation

Observe this matrix:

thismatrix = eye(5)
thismatrix =
 1     0     0     0     0
 0     1     0     0     0
 0     0     1     0     0
 0     0     0     1     0
 0     0     0     0     1

I wish to replace the zeros on either size of the 1's on every row with values descending from 1 by 0.1.

This is what I want:

thismatrix = 
1.0000    0.9000    0.8000    0.7000    0.6000       
0.9000    1.0000    0.9000    0.8000    0.7000    
0.8000    0.9000    1.0000    0.9000    0.8000   
0.7000    0.8000    0.9000    1.0000    0.9000    
0.6000    0.7000    0.8000    0.9000    1.0000

How can I accomplish this without numerous "for loops"/spaghetti code (especially if my matrix is larger)?

Best Answer

toeplitz(1:-.1:.6)

1 - abs((1:5) - (1:5)')*.1

Related Solutions

MATLAB: How to compare the elements of a matrix and fill another matrix with the elements of a vector

Since your t matrix is full of 0 and 1 you can take advantage of that and just do this

a = [0.9 0.8 0.7 0.6 0.5];
b = [0.1 0.2 0.3 0.4 0.5];
t = ff2n(n);
t1 = t.*a
t1 =
         0         0         0         0         0
         0         0         0         0    0.5000
         0         0         0    0.6000         0
         0         0         0    0.6000    0.5000
         0         0    0.7000         0         0
         0         0    0.7000         0    0.5000
         0         0    0.7000    0.6000         0
         0         0    0.7000    0.6000    0.5000
         0    0.8000         0         0         0
         0    0.8000         0         0    0.5000
         0    0.8000         0    0.6000         0
         0    0.8000         0    0.6000    0.5000
         0    0.8000    0.7000         0         0
         0    0.8000    0.7000         0    0.5000
         0    0.8000    0.7000    0.6000         0
         0    0.8000    0.7000    0.6000    0.5000
    0.9000         0         0         0         0
    0.9000         0         0         0    0.5000
    0.9000         0         0    0.6000         0
    0.9000         0         0    0.6000    0.5000
    0.9000         0    0.7000         0         0
    0.9000         0    0.7000         0    0.5000
    0.9000         0    0.7000    0.6000         0
    0.9000         0    0.7000    0.6000    0.5000
    0.9000    0.8000         0         0         0
    0.9000    0.8000         0         0    0.5000
    0.9000    0.8000         0    0.6000         0
    0.9000    0.8000         0    0.6000    0.5000
    0.9000    0.8000    0.7000         0         0
    0.9000    0.8000    0.7000         0    0.5000
    0.9000    0.8000    0.7000    0.6000         0
    0.9000    0.8000    0.7000    0.6000    0.5000
t2 = not(t.*a).*b
t2 =
    0.1000    0.2000    0.3000    0.4000    0.5000
    0.1000    0.2000    0.3000    0.4000         0
    0.1000    0.2000    0.3000         0    0.5000
    0.1000    0.2000    0.3000         0         0
    0.1000    0.2000         0    0.4000    0.5000
    0.1000    0.2000         0    0.4000         0
    0.1000    0.2000         0         0    0.5000
    0.1000    0.2000         0         0         0
    0.1000         0    0.3000    0.4000    0.5000
    0.1000         0    0.3000    0.4000         0
    0.1000         0    0.3000         0    0.5000
    0.1000         0    0.3000         0         0
    0.1000         0         0    0.4000    0.5000
    0.1000         0         0    0.4000         0
    0.1000         0         0         0    0.5000
    0.1000         0         0         0         0
         0    0.2000    0.3000    0.4000    0.5000
         0    0.2000    0.3000    0.4000         0
         0    0.2000    0.3000         0    0.5000
         0    0.2000    0.3000         0         0
         0    0.2000         0    0.4000    0.5000
         0    0.2000         0    0.4000         0
         0    0.2000         0         0    0.5000
         0    0.2000         0         0         0
         0         0    0.3000    0.4000    0.5000
         0         0    0.3000    0.4000         0
         0         0    0.3000         0    0.5000
         0         0    0.3000         0         0
         0         0         0    0.4000    0.5000
         0         0         0    0.4000         0
         0         0         0         0    0.5000
         0         0         0         0         0
t1+t2
ans =
    0.1000    0.2000    0.3000    0.4000    0.5000
    0.1000    0.2000    0.3000    0.4000    0.5000
    0.1000    0.2000    0.3000    0.6000    0.5000
    0.1000    0.2000    0.3000    0.6000    0.5000
    0.1000    0.2000    0.7000    0.4000    0.5000
    0.1000    0.2000    0.7000    0.4000    0.5000
    0.1000    0.2000    0.7000    0.6000    0.5000
    0.1000    0.2000    0.7000    0.6000    0.5000
    0.1000    0.8000    0.3000    0.4000    0.5000
    0.1000    0.8000    0.3000    0.4000    0.5000
    0.1000    0.8000    0.3000    0.6000    0.5000
    0.1000    0.8000    0.3000    0.6000    0.5000
    0.1000    0.8000    0.7000    0.4000    0.5000
    0.1000    0.8000    0.7000    0.4000    0.5000
    0.1000    0.8000    0.7000    0.6000    0.5000
    0.1000    0.8000    0.7000    0.6000    0.5000
    0.9000    0.2000    0.3000    0.4000    0.5000
    0.9000    0.2000    0.3000    0.4000    0.5000
    0.9000    0.2000    0.3000    0.6000    0.5000
    0.9000    0.2000    0.3000    0.6000    0.5000
    0.9000    0.2000    0.7000    0.4000    0.5000
    0.9000    0.2000    0.7000    0.4000    0.5000
    0.9000    0.2000    0.7000    0.6000    0.5000
    0.9000    0.2000    0.7000    0.6000    0.5000
    0.9000    0.8000    0.3000    0.4000    0.5000
    0.9000    0.8000    0.3000    0.4000    0.5000
    0.9000    0.8000    0.3000    0.6000    0.5000
    0.9000    0.8000    0.3000    0.6000    0.5000
    0.9000    0.8000    0.7000    0.4000    0.5000
    0.9000    0.8000    0.7000    0.4000    0.5000
    0.9000    0.8000    0.7000    0.6000    0.5000
    0.9000    0.8000    0.7000    0.6000    0.5000

MATLAB: How to make a permanent change to a matrix using sortrows

 P = sortrows(P,7) ;

Most of the time functions don't operate "externally", so SORTROWS doesn't alter your array P defined in the workspace. It creates a new sorted array that it outputs. You have to store this output back into P if you want P to be the sorted version. If you wanted to keep the original, you could store it into a new variable:

 P_sorted = sortrows(P,7) ;

Best Answer

Related Solutions

MATLAB: How to compare the elements of a matrix and fill another matrix with the elements of a vector

MATLAB: How to make a permanent change to a matrix using sortrows

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