You just have to be aware of potential indexing issues that can arrise. Obviously you can replace the value between the two : to be a step size that you want. It would look like this: for index = someValue:-1:1 You can also do every 4th index while going backwards for index = someValue:-4:1. In this case you start at the 'end' and move to the beginning. Yet another modfication is traversing backwards. All you have to do is: for index = 2:3:someValue The 3 here tells the loop that it should add 3 to the index at the end of each loop iteration until you get to (or surpass) someValue. You can modify this as well though! Let's say you want every 3rd index starting with the 2nd position in the matrix. Many times it's simply the last index value of a matrix you're wanting to traverse. SomeValue can really be anything that is greater than 1 in this case. The general syntax is for index = 1:someValue ![]() I will also open this up for community wiki so others can just easily edit this as well. There are two main ways that I can think of off the top of my head. I can't help with the matlab notation unfortunaly.Generally you and iterate multiple ways. 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. 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. OutArgs = cellfun(fcn, A, 'UniformOutput', false) 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. If A is a cell array of arbitrary dimension, you can use cellfun to apply my_func to each cell: outArgs = cellfun(fcn, A) 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. (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 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. The idea of a linear index for arrays in matlab is an important one.
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