reshape a matrix and fill empty indices by zeroes

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Fatma Alnabrisi
Fatma Alnabrisi 2019-12-9
编辑： dpb 2019-12-9
I'm woking in encryption project.
I have the key sequare matrix A for example with dimension mxm
I need to reshape the plaintext matrix P to be with same number of rows as A which is m
Now if the size of P devided by m equals an integer, this would be fine
however if it is not the new matrix P after reshaping will need more elemnets
So, how to write a function to fill the matrix P with zeroes after reshaping.
here's my code:
A = input('Enter Your key= ','t'); %key matrix mxm
sA = size (A);
sA = sA(1,1);
m = sA;
Ax = reshape (A , m , m );
disp (Ax);
x =input('Enter Your Message= ','s'); %plain text
sX = length(x);
n = round(sX/m);
if rem(sX, m) == 0
xR = reshape(x , m ,n);
else
???????????????
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dpb
dpb 2019-12-9
编辑：dpb 2019-12-9
Did something wrong then...
>> b=char({'fred';'flintstone'}) % sample text array 20 char mimic a small text file
b =
2×10 char array
'fred '
'flintstone'
>> [reshape(b.',1,[]) blanks(25-numel(b))] % the augmented vector intermediary
ans =
'fred flintstone '
>> reshape([reshape(b.',1,[]) blanks(25-numel(b))],5,[]) % the mxm (m=5) array
ans =
5×5 char array
'f fs '
'r lt '
'e io '
'd nn '
' te '
>>
Of course, in general the 25 is value of m*m and the 5 is m; just used a convenient number to illustrate.
dpb
dpb 2019-12-9
编辑：dpb 2019-12-9
In addition, the above is still a char() array, dunno what you intend to do when you speak of multiplying it with another array. You talk of augmenting w/ zero; the above used blanks instead with text, char(0) is also possible, of course.
>> double(ans)
ans =
102 32 102 115 32
114 32 108 116 32
101 32 105 111 32
100 32 110 110 32
32 32 116 101 32
>>
is the numeric represenation of above...as noted, I've no klew regarding what it is you're actually trying to do here.
Oh...one other thought--
>> char(ans).'
ans =
5×5 char array
'fred '
' '
'flint'
'stone'
' '
>>
Dunno which orientation you would prefer or if it matters...you may want to transpose the previous result?

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