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In MATLAB, we can operate on both rows and columns of a matrix. What does it exactly mean by "row major" or "column major"?
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Indexing with a Single Index This method is known as linear indexing. While MATLAB displays arrays according to their defined sizes and shapes, they are actually stored in memory as a single column of elements.
It only shows that in C language, 2-D arrays are stored in row major order and thus iterating its elements in a row major order is more efficient. In languages like Pascal and Fortran, iterating by column major order will be more efficient because 2-D arrays are stored in column major order there.
"Multidimensional arrays in Julia are stored in column-major order. This means that arrays are stacked one column at a time.
GLM stores matrices in column-major order. Note that row-major versus column-major is purely about memory layout on computers.
In MATLAB, arrays are stored in column major order. It means that when you have a multi-dimensional array, its 1D representation in memory is such that leftmost indices change faster.
MATLAB ® and Fortran use column-major layout by default, whereas C and C++ use row-major layout. With MATLAB Coder™, you can generate C/C++ code that uses row-major layout or column-major layout. See Generate Code That Uses Row-Major Array Layout. Computer memory stores data in terms of one-dimensional arrays.
In MATLAB, we can operate on both rows and columns of a matrix. What does it exactly mean by "row major" or "column major"? Show activity on this post.
By default, MATLAB stores these elements with a column-major array layout. The elements of each column are contiguous in memory. The matrix A is represented in memory by default with this arrangement: In row-major array layout, the programming language stores row elements contiguously in memory.
It is important to understand that MATLAB stores data in column-major order, so you know what happens when you apply the colon operator without any commas:
>> M = magic(3) M = 8 1 6 3 5 7 4 9 2 >> M(:) ans = 8 3 4 1 5 9 6 7 2 I tend to think "MATLAB goes down, then across". This makes it easy to reshape and permute arrays without scrambling your data. It's also necessary in order to grasp linear indexing (e.g. M(4)).
For example, a common way to obtain a column vector inline from some expression that generates an array is:
reshape(<array expression>,[],1) As with (:) this stacks all the columns on top of each other into single column vector, for all data in any higher dimensions. But this nifty syntactic trick lets you avoid an extra line of code.
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In MATLAB, arrays are stored in column major order.
It means that when you have a multi-dimensional array, its 1D representation in memory is such that leftmost indices change faster.
It's called column major order because for a 2D array (matrix), the first (leftmost) index is typically the row index, so since it changes faster than the second (next to the right) index, the 1D representation of the matrix is memory correspond to the concatenation of the columns of the matrix.
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