question regarding sum(m,3) command
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hello, i have a three dimentional matrices m.
output of sum(m,3) return a two dimentional matrices.
What kind of summing being done on my 3D matrices which creates the 2D matrices?
Thanks.
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Jan
il 13 Dic 2022
Modificato: Jan
il 13 Dic 2022
Actually a sum over a 3D array along the 3rd dimension replies a [M x N x 1] array, as summing over the 2nd dimension creates a [M x 1 X P] array. But Matlab ignores trailing singelton dimensions, except it is the 2nd dimension of a matrix (known as "column vector").
You can even access these virtual dimensions:
X = [1, 2; 3, 4]
X(1, 2, 1)
X(2, 2, 1, 1, 1, 1, 1)
There have been some inconsistencies in R2009a, which let trailing singelton dimensions exist for some functions implemented a C-mex. This did not cause bugs, but the ndims command counted this virtual dimensions also. In modern Matlab version, this feature is supported consequently as far as I know.
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