I can't help with the matlab notation unfortunaly. That way you can simulate nested for loops that begin somewhere in the table and finish not at the end. You can do it in such way that you can start with any value of the number and increase/decrease the digits by any numbers.
#MATLAB MATRIX CODE#
So you can write the code for increasing such n-digit number. We have to increase the number, so we would get the sequence 0 0 0 We have 3 digit number, with 3 digits for first, 4 for second and five for third digit To simulate this you would have to use the "n-digit number notation" In "for notation" we have: for(int x=0 x<3 x++) Suppose we had array(matrix) int T=new int Iterating through n-dimmensional array can be seen as increasing the n-digit number.Īt each dimmension we have as many digits as the lenght of the dimmension. When referring to parts of a matrix, it's common to use the term 'element', and reserve the term 'cell' to refer to parts of a cell array. The most important are: struct, matrix, and cell array. OutArgs = cellfun(fcn, A, 'UniformOutput', false) Matlab terminology note: Matlab has a small number of core data types. This is done by calling either arrayfun or cellfun with an additional parameter/value pair: outArgs = arrayfun(fcn, A, 'UniformOutput', false) if my_func returns outputs of different sizes and types when it operates on different elements of A, then outArgs will have to be made into a cell array. If there are any outputs from my_func, these are placed in outArgs, which will be the same size/dimension as A. The function my_func has to accept A as an input. Compare two versions that calculate the following formula for each element of two m n matrices zx2siny Bad version for i 1:m for j 1:n z(i,j) x(i,j)2sin(y(i,j)) end end Good version z x.2. If A is a cell array of arbitrary dimension, you can use cellfun to apply my_func to each cell: outArgs = cellfun(fcn, A) MATLAB code performance This is the key to writing fast code in MATLAB. You first create a function handle to this function: fcn = A is a matrix (of type double, single, etc.) of arbitrary dimension, you can use arrayfun to apply my_func to each element: outArgs = arrayfun(fcn, A) Let's first assume you have a function that you want to apply to each element of A (called my_func). There are also a couple of functions you can use: arrayfun and cellfun.
#MATLAB MATRIX 64 BIT#
(Though I don't use a 64 bit MATLAB release, I believe that problem has been resolved for those lucky individuals who do.)Īs pointed out in a few other answers, you can iterate over all elements in a matrix A (of any dimension) using a linear index from 1 to numel(A) in a single for loop. It is really only an issue if you use sparse matrices often, when occasionally this will cause a problem. So if your array has more then a total of 2^32 elements in it, the linear index will fail.
#MATLAB MATRIX 32 BIT#
MATLAB uses a 32 bit integer to store these indexes. The only problem with the linear index is when they get too large. So you can use it on structures, cell arrays, etc. The linear index applies in general to any array in matlab. Conversion between the linear index and two (or higher) dimensional subscripts is accomplished with the sub2ind and ind2sub functions. There are many circumstances where the linear index is more useful. For example, if we wanted to square the elements of A (yes, I know there are better ways to do this), one might do this: B = zeros(size(A))
The result is, we can access each element in turn of a general n-d array using a single loop. In fact, the function find returns its results as a linear index. A(:)Īs you can see, the 8th element is the number 7. We can see the order the elements are stored in memory by unrolling the array into a vector. MATLAB allows you to use either a row and column index, or a single linear index. An array in MATLAB is really just a vector of elements, strung out in memory. In this case, the right side must contain the same number of elements as A.The idea of a linear index for arrays in matlab is an important one. On the left side of an assignment statement, A(:) fills A, preserving its shape from before. Is all the elements of A, regarded as a single column. Is the k th page of three-dimensional array A. The following table describes its use for this purpose (let us have a matrix A) − Format You can use the colon operator to create a vector of indices to select rows, columns or elements of arrays.
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