> Berwin A Turlach
> on Wed, 28 Feb 2024 17:42:27 +0800 writes:
> On Tue, 27 Feb 2024 13:51:25 -0800 Jeff Newmiller via
> R-help wrote:
>> The fundamental data type in Matlab is a matrix... they
>> don't have vectors, they have Nx1 matrices and 1xM
>> matrices.
The first vector-oriented programming language I ever learned or used
was APL, and APL makes *no* distinction between row vectors and column
vectors. It has rank-0 (scalar), rank-1 (vector), rank-2 (matrix),
rank-3 ... and so on arrays. A rank-1 array is a rank-1 array is a
rank-1 array and
Agree that sweep is the tool here. (If you think it is clunky, check how more
general array-sweep operations can be done in Matlab.)
However, it isn't really true that sweep isn't moving things around. Notice
the call to aperm() at the end of the code for sweep():
perm <- c(MARGIN,
On Tue, 27 Feb 2024 14:54:26 -0500
Evan Cooch wrote:
> So, trying to convert a very long, somewhat technical bit of lin alg
> MATLAB code to R. Most of it working, but raninto a stumbling block
> that is probaably simple enough for someone to explain.
On
On Tue, 27 Feb 2024 13:51:25 -0800
Jeff Newmiller via R-help wrote:
> The fundamental data type in Matlab is a matrix... they don't have
> vectors, they have Nx1 matrices and 1xM matrices.
Also known as column vectors and row vectors. :)
> Vectors don't have any concept of "row" vs.
... and here is a more or less direct translation of the Matlab code that
should now be obvious given your previous responses:
> m <- matrix(1:6, nr=2, byrow = TRUE) ## Matlab order
> m
[,1] [,2] [,3]
[1,]123
[2,]456
> sweep(m, 2, 2:4, "/")
[,1] [,2] [,3]
Why anything but sweep?
The fundamental data type in Matlab is a matrix... they don't have vectors,
they have Nx1 matrices and 1xM matrices.
Vectors don't have any concept of "row" vs. "column". Straight division is
always elementwise with recycling as needed, and matrices are really vectors
So, trying to convert a very long, somewhat technical bit of lin alg
MATLAB code to R. Most of it working, but raninto a stumbling block that
is probaably simple enough for someone to explain.
Basically, trying to 'line up' MATLAB results from an element-wise
division of a matrix by a vector
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