Reshape symbolic array
reshape( lets
you represent a size value with the placeholder A,...,[],...)[] while
calculating the magnitude of that size value automatically. For example,
if A has size 2-by-6, then reshape(A,4,[]) returns
a 4-by-3 array.
Reshape V, which is a 1-by-4 row vector, into the 4-by-1
column vector Y. Here, V and Y
must have the same number of elements.
Create the vector V.
syms f(x) y V = [3 f(x) -4 y]
V = [ 3, f(x), -4, y]
Reshape V into Y.
Y = reshape(V,4,1)
Y = 3 f(x) -4 y
Alternatively, use Y = V.' where .' is
the nonconjugate transpose.
Reshape the 2-by-6 symbolic matrix M into
a 4-by-3 matrix.
M = sym([1 9 4 3 0 1; 3 9 5 1 9 2]) N = reshape(M,4,3)
M = [ 1, 9, 4, 3, 0, 1] [ 3, 9, 5, 1, 9, 2] N = [ 1, 4, 0] [ 3, 5, 9] [ 9, 3, 1] [ 9, 1, 2]
M and N must have the
same number of elements. reshape reads M column-wise
to fill in the elements of N column-wise.
Alternatively, use a size vector to specify the dimensions of the reshaped matrix.
sz = [4 3]; N = reshape(M,sz)
N = [ 1, 4, 0] [ 3, 5, 9] [ 9, 3, 1] [ 9, 1, 2]
When you replace a dimension with the placeholder [], reshape calculates
the required magnitude of that dimension to reshape the matrix.
Create the matrix M.
M = sym([1 9 4 3 0 1; 3 9 5 1 9 2])
M = [ 1, 9, 4, 3, 0, 1] [ 3, 9, 5, 1, 9, 2]
Reshape M into a matrix with three columns.
reshape(M,[],3)
ans = [ 1, 4, 0] [ 3, 5, 9] [ 9, 3, 1] [ 9, 1, 2]
reshape calculates that a reshaped matrix
of three columns needs four rows.
Reshape a matrix row-wise by transposing the result.
Create matrix M.
syms x M = sym([1 9 0 sin(x) 2 2; NaN x 5 1 4 7])
M = [ 1, 9, 0, sin(x), 2, 2] [ NaN, x, 5, 1, 4, 7]
Reshape M row-wise by transposing the result.
reshape(M,4,3).'
ans = [ 1, NaN, 9, x] [ 0, 5, sin(x), 1] [ 2, 4, 2, 7]
Note that .' returns the non-conjugate transpose
while ' returns the conjugate transpose.
Reshape the 3-by-3-by-2 array M into
a 9-by-2 matrix.
M has 18 elements. Because a 9-by-2 matrix
also has 18 elements, M can be reshaped into it.
Construct M.
syms x M = [sin(x) x 4; 3 2 9; 8 x x]; M(:,:,2) = M'
M(:,:,1) = [ sin(x), x, 4] [ 3, 2, 9] [ 8, x, x] M(:,:,2) = [ sin(conj(x)), 3, 8] [ conj(x), 2, conj(x)] [ 4, 9, conj(x)]
Reshape M into a 9-by-2 matrix.
N = reshape(M,9,2)
N = [ sin(x), sin(conj(x))] [ 3, conj(x)] [ 8, 4] [ x, 3] [ 2, 2] [ x, 9] [ 4, 8] [ 9, conj(x)] [ x, conj(x)]
Use reshape instead of loops
to break up arrays for further computation. Use reshape to
break up the vector V to find the product of every
three elements.
Create vector V.
syms x V = [exp(x) 1 3 9 x 2 7 7 1 8 x^2 3 4 sin(x) x]
V = [ exp(x), 1, 3, 9, x, 2, 7, 7, 1, 8, x^2, 3, 4, sin(x), x]
Specify 3 for the number of rows. Use the
placeholder [] for the number of columns. This
lets reshape automatically calculate the number
of columns required for three rows.
M = prod( reshape(V,3,[]) )
M = [ 3*exp(x), 18*x, 49, 24*x^2, 4*x*sin(x)]
reshape calculates that five columns are
required for a matrix of three rows. prod then
multiples the elements of each column to return the result.