How to make a m*2 matrix into n number of 2x2 matrices

Hey,

I have, A = 208x2 matrix. I wish to to spit this matrix into 104 2x2 matrices. I have tried using num2cell and mat2cell but have had no luck. Any help would be appreicated.

Thanks.

[Dyl]

Thanks for the replies!

Answer 1

[Stephen23]

A = rand(208,2);
C = mat2cell(A,2*ones(104,1),2)

C = 104×1 cell array
    {2×2 double}
    {2×2 double}
    {2×2 double}
    {2×2 double}
    {2×2 double}
    {2×2 double}
    {2×2 double}
    {2×2 double}
    {2×2 double}
    {2×2 double}
    {2×2 double}
    {2×2 double}
    {2×2 double}
    {2×2 double}
    {2×2 double}
    {2×2 double}

[Dyl]

Thank you this works. I also have another question.

I wanted to create these 2x2 matrices so I could complete x=A\B to find the unknowns, the two forces acting upon a point. The 2x2 matrices is the matrices requried for each possible coordinate of the point subjected to two forces.

I have B = [0;62.4051] and when I try x=A\B it states there is an error 'Arguments must be numeric, char, or logical,' Do you know how I overcome this error?

[Dyl]

I will elaborate on this to ensure clarity.

There are two unknown forces F1 and F2. They are acting upon point J. Point J is in a carteisan grid and therefore, has x number of possible locations. I have calculated the matrices for each location of point J and x=A\B is to calculate the two unknown forces (F1 and F2) for each possible J point. That is why there are 104 2x2 matrices because I wish to solve the system of equations for each point. However, Matlab will not allow for the calculations because of the error stated above.

[Stephen23]

"I wanted to create these 2x2 matrices so I could complete x=A\B to find the unknowns..."

A = rand(208,2);
B = [0;62.4051];

1) loop over the cells, or use CELLFUN:

C = mat2cell(A,2*ones(104,1),2);
D = cellfun(@(a)a\B,C,'uni',0)

D = 104×1 cell array
    {2×1 double}
    {2×1 double}
    {2×1 double}
    {2×1 double}
    {2×1 double}
    {2×1 double}
    {2×1 double}
    {2×1 double}
    {2×1 double}
    {2×1 double}
    {2×1 double}
    {2×1 double}
    {2×1 double}
    {2×1 double}
    {2×1 double}
    {2×1 double}

D{1:5}

ans = 2×1

254.7375 -448.7160

ans = 2×1

-201.0346 269.0615

ans = 2×1

-15.4333 244.1028

ans = 2×1

-37.7452 115.8506

ans = 2×1

242.8873 -256.4729

2) avoid the cell array entirely: call PERMUTE&RESHAPE the data, and then call PAGEMLDIVIDE: https://www.mathworks.com/help/matlab/ref/pagemldivide.html

N = permute(reshape(A.',2,2,[]),[2,1,3]);
 Z = pagemldivide(N,B)

Z = 
Z(:,:,1) =

  254.7375
 -448.7160


Z(:,:,2) =

 -201.0346
  269.0615


Z(:,:,3) =

  -15.4333
  244.1028


Z(:,:,4) =

  -37.7452
  115.8506


Z(:,:,5) =

  242.8873
 -256.4729


Z(:,:,6) =

  399.4539
 -465.6991


Z(:,:,7) =

  103.4845
  -57.6442


Z(:,:,8) =

  201.3918
 -300.9553


Z(:,:,9) =

   71.7649
  -11.7430


Z(:,:,10) =

 -140.2163
  121.2142


Z(:,:,11) =

 -249.7239
  339.4336


Z(:,:,12) =

  -74.7253
   92.1409


Z(:,:,13) =

  -71.2602
   76.4186


Z(:,:,14) =

  -51.0881
  208.3873


Z(:,:,15) =

  137.9599
  -54.1809


Z(:,:,16) =

   87.1851
  -38.8293


Z(:,:,17) =

  213.9198
 -256.6160


Z(:,:,18) =

 -184.3306
  387.9273


Z(:,:,19) =

  -83.0493
  184.3273


Z(:,:,20) =

  190.0474
 -180.4605


Z(:,:,21) =

   93.1972
 -162.9662


Z(:,:,22) =

   1.0e+03 *

   -1.6875
    1.1888


Z(:,:,23) =

 -157.0278
  165.5029


Z(:,:,24) =

   1.0e+03 *

   -1.1328
    0.6363


Z(:,:,25) =

   1.0e+03 *

    2.7605
   -1.5682


Z(:,:,26) =

 -141.5120
  226.2982


Z(:,:,27) =

  457.9589
 -677.7478


Z(:,:,28) =

  -43.5975
  101.2070


Z(:,:,29) =

  294.5180
 -179.8068


Z(:,:,30) =

  455.4697
 -141.1948


Z(:,:,31) =

  174.2676
  -91.3634


Z(:,:,32) =

  291.5284
 -317.2197


Z(:,:,33) =

   1.0e+03 *

    2.6183
   -1.0546


Z(:,:,34) =

   1.0e+03 *

   -3.6468
    3.4186


Z(:,:,35) =

  -26.2973
   82.2843


Z(:,:,36) =

   92.9864
 -399.6707


Z(:,:,37) =

 -313.3782
  334.0579


Z(:,:,38) =

   1.0e+03 *

    0.5017
   -3.2983


Z(:,:,39) =

  -25.1379
   78.3355


Z(:,:,40) =

  -60.8443
  158.5588


Z(:,:,41) =

 -126.9928
  245.6587


Z(:,:,42) =

  138.7083
  -77.8317


Z(:,:,43) =

  -73.1815
   99.4966


Z(:,:,44) =

  -29.2873
  152.2512


Z(:,:,45) =

  117.8240
   -1.3511


Z(:,:,46) =

  377.8151
 -423.7863


Z(:,:,47) =

 -972.7903
  398.6766


Z(:,:,48) =

 -718.3835
  784.9308


Z(:,:,49) =

 -347.1907
  359.5996


Z(:,:,50) =

   1.0e+03 *

    3.4663
   -1.6957


Z(:,:,51) =

 -679.9005
  433.6712


Z(:,:,52) =

   85.1131
  -13.1754


Z(:,:,53) =

   74.8836
   -2.8372


Z(:,:,54) =

  139.1516
  -24.7928


Z(:,:,55) =

  -20.8858
  235.3895


Z(:,:,56) =

  -37.8064
  109.0375


Z(:,:,57) =

  -80.3218
   92.2070


Z(:,:,58) =

   1.0e+03 *

    1.1045
   -1.3925


Z(:,:,59) =

  178.5230
  -47.1629


Z(:,:,60) =

  407.5570
 -464.2490


Z(:,:,61) =

   1.0e+03 *

    1.7465
   -0.3442


Z(:,:,62) =

  -16.3257
  455.7497


Z(:,:,63) =

  -23.1154
  132.7811


Z(:,:,64) =

   1.0e+04 *

   -1.6290
    0.9430


Z(:,:,65) =

  -27.6003
   81.3097


Z(:,:,66) =

   1.0e+03 *

   -1.4705
    1.7093


Z(:,:,67) =

   1.0e+03 *

   -1.9158
    1.4897


Z(:,:,68) =

  690.1267
 -526.2135


Z(:,:,69) =

   86.3370
  -27.2462


Z(:,:,70) =

  -50.0804
  285.7423


Z(:,:,71) =

  -25.8221
   79.6419


Z(:,:,72) =

   81.4405
  -87.0205


Z(:,:,73) =

  -12.2335
   74.8112


Z(:,:,74) =

   1.0e+03 *

   -0.5944
    1.2712


Z(:,:,75) =

  112.3409
  -86.8035


Z(:,:,76) =

   98.5285
  -13.9627


Z(:,:,77) =

 -149.9494
  175.6624


Z(:,:,78) =

  167.1853
  -77.1778


Z(:,:,79) =

  174.2291
 -206.0751


Z(:,:,80) =

  113.1018
  -19.5503


Z(:,:,81) =

  215.3669
  -47.3075


Z(:,:,82) =

 -162.0178
  200.6032


Z(:,:,83) =

  885.2354
 -250.7677


Z(:,:,84) =

  256.4040
 -164.9046


Z(:,:,85) =

   1.0e+03 *

   -0.0817
    1.3533


Z(:,:,86) =

  -23.8031
   74.5642


Z(:,:,87) =

 -124.8749
  114.4583


Z(:,:,88) =

  -56.6865
  151.5106


Z(:,:,89) =

  -20.6243
   84.8720


Z(:,:,90) =

   81.2266
  -30.3164


Z(:,:,91) =

   82.7109
  -16.0798


Z(:,:,92) =

  255.3523
 -206.2097


Z(:,:,93) =

 -423.2773
  196.9388


Z(:,:,94) =

   1.0e+03 *

   -0.4201
    1.9390


Z(:,:,95) =

  321.7179
  -89.7420


Z(:,:,96) =

 -306.0857
  229.0526


Z(:,:,97) =

  -31.1052
   97.7231


Z(:,:,98) =

  128.2371
 -167.8192


Z(:,:,99) =

  107.3783
  -63.8622


Z(:,:,100) =

   1.0e+03 *

   -1.1572
    0.8569


Z(:,:,101) =

  262.9194
 -369.1406


Z(:,:,102) =

  -59.1690
  144.2688


Z(:,:,103) =

  226.9019
 -171.2881


Z(:,:,104) =

   73.9992
  -38.2548

[Dyl]

Thank you

[Dyl]

Hey I have another question I reshaped the 2x1x104 matrix into a 13x8 matrix where I only took one value for each val(:,:,1) , valu(:,:,2) etc..

13x8 = [-28,-64 ... ;-33,-74...]

I wanted the values to insert into the 13x8 matric column wise so 1-8 for row 1 then 1-8 for row 2 so on, but they inserted row wise. How can I make the matrix I am after? Thanks in advance.

[Stephen23]

M = reshape(M,8,13).'

Answer 2

[KSSV]

A = rand(208,2) ;

[r,c] = size(A);
nlay  = 104 ;
out   = permute(reshape(A',[c,r/nlay,nlay]),[2,1,3]);

Answer 3

[Abderrahim. B]

Split A

A = randi(10, 208, 2) ;  % a mtarix of size 208x2
size(A)

ans = 1×2

208 2

B = reshape(A, 2, 2, []) ;

Access 2x2 matrices

B1 = B(:,:,1) 

B1 = 2×2

5 7 9 6

B2 = B(:,:,2)

B2 = 2×2

8 8 4 1

Hope this helps

[Stephen23]

Note that this method does not keep the 2x2 matrices of the original matrix:

A = randi(10, 208, 2)

A = 208×2

3 1 9 7 9 3 4 9 8 7 5 5 4 4 9 1 8 10 10 8

B = reshape(A, 2,2,[]) % not the same matrices

B = 
B(:,:,1) =
     3     9
     9     4
B(:,:,2) =
     8     4
     5     9
B(:,:,3) =
     8     5
    10     4
B(:,:,4) =
     2     1
    10    10
B(:,:,5) =
     2     5
     7     9
B(:,:,6) =
     4     7
     4     9
B(:,:,7) =
     6     9
     4     6
B(:,:,8) =
    10     9
     2     3
B(:,:,9) =
    10     4
     6     4
B(:,:,10) =
     8     5
     2     5
B(:,:,11) =
     4     2
     6     4
B(:,:,12) =
     5     1
     6     8
B(:,:,13) =
     7     4
     4     6
B(:,:,14) =
     3     7
     6     6
B(:,:,15) =
     4     4
     7     9
B(:,:,16) =
     9     6
     2    10
B(:,:,17) =
     8     9
     7     6
B(:,:,18) =
     3     3
     2     4
B(:,:,19) =
     6     1
     6     3
B(:,:,20) =
     4     3
    10    10
B(:,:,21) =
     5     9
     6     5
B(:,:,22) =
     2     2
     8    10
B(:,:,23) =
     4     8
     3     7
B(:,:,24) =
     9     7
     2     3
B(:,:,25) =
     8    10
     6     9
B(:,:,26) =
     6     7
     8     4
B(:,:,27) =
     7    10
    10     1
B(:,:,28) =
     3     9
     7     4
B(:,:,29) =
     4     3
     9    10
B(:,:,30) =
     4     5
     3     2
B(:,:,31) =
     2     5
     9     5
B(:,:,32) =
     2     9
     9     4
B(:,:,33) =
     2     1
     6     9
B(:,:,34) =
     8     1
     3     4
B(:,:,35) =
     2     4
     4     3
B(:,:,36) =
     7     1
     5     4
B(:,:,37) =
    10     7
     1    10
B(:,:,38) =
     8     1
     1    10
B(:,:,39) =
    10     4
     1     8
B(:,:,40) =
     2     7
     9     7
B(:,:,41) =
     3    10
     2     7
B(:,:,42) =
     8     5
     9     5
B(:,:,43) =
     3    10
    10     1
B(:,:,44) =
     7     9
     2     3
B(:,:,45) =
     2    10
     9    10
B(:,:,46) =
     8     1
     9     6
B(:,:,47) =
     5     8
     7     9
B(:,:,48) =
     2     2
     3     2
B(:,:,49) =
     3     2
     3     5
B(:,:,50) =
     4     2
     9     3
B(:,:,51) =
     7    10
    10     3
B(:,:,52) =
     9     5
     3     3
B(:,:,53) =
     1     3
     7     9
B(:,:,54) =
     7     4
     5     1
B(:,:,55) =
    10     2
     8    10
B(:,:,56) =
     7     8
     8     4
B(:,:,57) =
     3     3
     6     1
B(:,:,58) =
     9     2
     5     6
B(:,:,59) =
    10     9
     6     3
B(:,:,60) =
     1     9
     5     4
B(:,:,61) =
     5     9
     4     3
B(:,:,62) =
     7     9
     8     5
B(:,:,63) =
     3     7
     3    10
B(:,:,64) =
     8    10
    10     8
B(:,:,65) =
     6    10
     9     4
B(:,:,66) =
     8     2
     7     3
B(:,:,67) =
     3     6
     5     3
B(:,:,68) =
     7     5
     5     6
B(:,:,69) =
     3     6
     6    10
B(:,:,70) =
     4     4
     6     1
B(:,:,71) =
     2     7
     6     8
B(:,:,72) =
     1     6
     1     5
B(:,:,73) =
     7     1
    10     1
B(:,:,74) =
     1     3
     4     6
B(:,:,75) =
     1     4
     5     9
B(:,:,76) =
    10    10
     9     1
B(:,:,77) =
    10     2
     4     4
B(:,:,78) =
     4     8
     8     3
B(:,:,79) =
    10     1
    10     8
B(:,:,80) =
     6     5
     7     9
B(:,:,81) =
    10     9
     8     5
B(:,:,82) =
     5     5
     5     8
B(:,:,83) =
     1     8
     5     1
B(:,:,84) =
    10     4
     4     8
B(:,:,85) =
     8     7
     6     4
B(:,:,86) =
     4    10
     4     2
B(:,:,87) =
     9     6
     3     2
B(:,:,88) =
     9     7
     9     7
B(:,:,89) =
    10     8
    10     7
B(:,:,90) =
     1     3
     9     4
B(:,:,91) =
     7     4
     1     8
B(:,:,92) =
    10     9
     5     9
B(:,:,93) =
     2     4
     6     8
B(:,:,94) =
     6     3
     7    10
B(:,:,95) =
    10     9
    10     2
B(:,:,96) =
    10     5
     3     2
B(:,:,97) =
    10     4
     9     4
B(:,:,98) =
    10     5
     9     8
B(:,:,99) =
     5     7
     6     7
B(:,:,100) =
     7    10
     1     9
B(:,:,101) =
     1     2
     7     9
B(:,:,102) =
     8     3
     5     6
B(:,:,103) =
    10    10
     4     8
B(:,:,104) =
     6    10
     3     4

To keep the original matrices requires taing into account the order of elements stored in memory:

B = permute(reshape(A.',2,2,[]),[2,1,3])

B = 
B(:,:,1) =
     3     1
     9     7
B(:,:,2) =
     9     3
     4     9
B(:,:,3) =
     8     7
     5     5
B(:,:,4) =
     4     4
     9     1
B(:,:,5) =
     8    10
    10     8
B(:,:,6) =
     5     2
     4    10
B(:,:,7) =
     2     7
    10     8
B(:,:,8) =
     1     8
    10     4
B(:,:,9) =
     2     3
     7     6
B(:,:,10) =
     5     3
     9     1
B(:,:,11) =
     4     9
     4     5
B(:,:,12) =
     7     2
     9     6
B(:,:,13) =
     6    10
     4     6
B(:,:,14) =
     9     9
     6     3
B(:,:,15) =
    10     1
     2     5
B(:,:,16) =
     9     9
     3     4
B(:,:,17) =
    10     5
     6     4
B(:,:,18) =
     4     9
     4     3
B(:,:,19) =
     8     7
     2     8
B(:,:,20) =
     5     9
     5     5
B(:,:,21) =
     4     3
     6     3
B(:,:,22) =
     2     7
     4    10
B(:,:,23) =
     5     8
     6    10
B(:,:,24) =
     1    10
     8     8
B(:,:,25) =
     7     6
     4     9
B(:,:,26) =
     4    10
     6     4
B(:,:,27) =
     3     8
     6     7
B(:,:,28) =
     7     2
     6     3
B(:,:,29) =
     4     3
     7     5
B(:,:,30) =
     4     6
     9     3
B(:,:,31) =
     9     7
     2     5
B(:,:,32) =
     6     5
    10     6
B(:,:,33) =
     8     3
     7     6
B(:,:,34) =
     9     6
     6    10
B(:,:,35) =
     3     4
     2     6
B(:,:,36) =
     3     4
     4     1
B(:,:,37) =
     6     2
     6     6
B(:,:,38) =
     1     7
     3     8
B(:,:,39) =
     4     1
    10     1
B(:,:,40) =
     3     6
    10     5
B(:,:,41) =
     5     7
     6    10
B(:,:,42) =
     9     1
     5     1
B(:,:,43) =
     2     1
     8     4
B(:,:,44) =
     2     3
    10     6
B(:,:,45) =
     4     1
     3     5
B(:,:,46) =
     8     4
     7     9
B(:,:,47) =
     9    10
     2     9
B(:,:,48) =
     7    10
     3     1
B(:,:,49) =
     8    10
     6     4
B(:,:,50) =
    10     2
     9     4
B(:,:,51) =
     6     4
     8     8
B(:,:,52) =
     7     8
     4     3
B(:,:,53) =
     7    10
    10    10
B(:,:,54) =
    10     1
     1     8
B(:,:,55) =
     3     6
     7     7
B(:,:,56) =
     9     5
     4     9
B(:,:,57) =
     4    10
     9     8
B(:,:,58) =
     3     9
    10     5
B(:,:,59) =
     4     5
     3     5
B(:,:,60) =
     5     5
     2     8
B(:,:,61) =
     2     1
     9     5
B(:,:,62) =
     5     8
     5     1
B(:,:,63) =
     2    10
     9     4
B(:,:,64) =
     9     4
     4     8
B(:,:,65) =
     2     8
     6     6
B(:,:,66) =
     1     7
     9     4
B(:,:,67) =
     8     4
     3     4
B(:,:,68) =
     1    10
     4     2
B(:,:,69) =
     2     9
     4     3
B(:,:,70) =
     4     6
     3     2
B(:,:,71) =
     7     9
     5     9
B(:,:,72) =
     1     7
     4     7
B(:,:,73) =
    10    10
     1    10
B(:,:,74) =
     7     8
    10     7
B(:,:,75) =
     8     1
     1     9
B(:,:,76) =
     1     3
    10     4
B(:,:,77) =
    10     7
     1     1
B(:,:,78) =
     4     4
     8     8
B(:,:,79) =
     2    10
     9     5
B(:,:,80) =
     7     9
     7     9
B(:,:,81) =
     3     2
     2     6
B(:,:,82) =
    10     4
     7     8
B(:,:,83) =
     8     6
     9     7
B(:,:,84) =
     5     3
     5    10
B(:,:,85) =
     3    10
    10    10
B(:,:,86) =
    10     9
     1     2
B(:,:,87) =
     7    10
     2     3
B(:,:,88) =
     9     5
     3     2
B(:,:,89) =
     2    10
     9     9
B(:,:,90) =
    10     4
    10     4
B(:,:,91) =
     8    10
     9     9
B(:,:,92) =
     1     5
     6     8
B(:,:,93) =
     5     5
     7     6
B(:,:,94) =
     8     7
     9     7
B(:,:,95) =
     2     7
     3     1
B(:,:,96) =
     2    10
     2     9
B(:,:,97) =
     3     1
     3     7
B(:,:,98) =
     2     2
     5     9
B(:,:,99) =
     4     8
     9     5
B(:,:,100) =
     2     3
     3     6
B(:,:,101) =
     7    10
    10     4
B(:,:,102) =
    10    10
     3     8
B(:,:,103) =
     9     6
     3     3
B(:,:,104) =
     5    10
     3     4

[Abderrahim. B]

Thanks @Stephen23. But he does not mention that the order must be te same as in the original matrix!