MATLAB: Fastest way to multiply each block of an array with another matrix

matrixmultiple

Hello all,

I have a 12x4xN array which I would like to multiply each 12×4 block by a 4×16 matrix in order to get a 12x16xN array. Could somebody please help me with a fast way of doing that? Thank you!

Best Answer

If you have a C compiler:

A = your 12 x 4 x N array;
B = your 4 x 16 matrix;
out = mtimesx(A,B);

You can find mtimesx here:

http://www.mathworks.com/matlabcentral/fileexchange/25977-mtimesx-fast-matrix-multiply-with-multi-dimensional-support

If you don't have a C compiler, then you can try MULTIPROD:

http://www.mathworks.com/matlabcentral/fileexchange/8773-multiple-matrix-multiplications--with-array-expansion-enabled

Related Solutions

MATLAB: Create matrix with different column size from a time series

X = [10, 12, 13, 18] ;
Xn = cell(length(X),1) ;
for i = 1:length(X)
    Xn{i} = X(1:i) ;
end
celldisp(Xn)

MATLAB: Please, anyone who can handle with the warning message; (Warning: Explicit solution could not be found. > In solve at 169).

With this code:

syms x y z t real
Sa=2*pi*30^2*(1-sin(pi/18))+2*pi*t*(30*cos(pi/18)+(t/2)*tan(pi/18))/cos(pi/18);
Sa = simplify(Sa, 'steps', 10);
Sb=170^2-pi*30^2;
F=-0.3*Sa/(1+x)+((Sa*x^2)/(1+x)+(Sb*y^2)/(1+y))/2+z*(Sa/(1+x)+Sb/(1+y)-(170^2)/1.1);
F = simplify(F, 'steps',10);
[x,y,z,t] = solve((x^2)/2+x+0.3-z==0, (y^2)/2+y-z==0, (1+x)*((170^2)/(1.1)-(Sb)/(1+y))==Sa, F==0, [x, y, z, t])

and after several minutes (I didn’t time it), I got:

x =
-1.0
y =
-0.22540333075851662296414692004352
z =
-0.2
t =
-26.959447166136052326594445120517

Best Answer

Related Solutions

MATLAB: Create matrix with different column size from a time series

MATLAB: Please, anyone who can handle with the warning message; (Warning: Explicit solution could not be found. > In solve at 169).

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