w = waitbar(0, 'My Progress Bar') % create a new waitbar, w with 0% progress for i=1:500 (To be precise, Octave has a waitbar function, but does not support all of the same operations, e.g. Note, however, that this doesn't currently work in Octave. MATLAB's graphical progress bar can be a useful tool for getting a sense of how long operations are taking, particularly ones involving loops. Note that the process of publishing this document can throw off the timing results - try the code out for yourself. Tom Minka has written some flop counting routines as part of his lightspeed package. MATLAB used to have a flops command, but it was removed. While this is usually very fast, you will sometimes notice that a function is faster to execute the second time round. The first time a function is called, MATLAB generates an optimized p-code file. A more reliable method is the timeit function, which calls tic/toc multiple times and averages. The simplest way to time code is to call tic before your code starts and toc afterwords. The profiler tells you where all the time is being spent, but maybe you just want to know how much time your code is taking. Once profiling is on, execute your code, and then type profile viewer to see the report. You can turn on profiling with the profile on command and turn it off again with profile off. You can click on a function name to bring up its sourcecode. This is really the statistic you should pay attention to. Self-time, denoted by a dark blue band, is the time spent within a function not including how long was spent in functions called from here. The report shows a breakdown of all the functions called from your function, the number of times they were called, and the total time spent executing them. It automatically generates a web page summarizing the results, which you can click on to 'drill down'. MATLAB has an excellent profiler, which can tell you how much time your code spends in each one of its functions. Also, remember that correctness is more important than speed! The usual pattern is that 80% of the the time is spent in 20% of the code, so you can focus your efforts accordingly. A slightly more complex example of vectorizationīefore spending a lot of time optimizing your code, you should first identify the key bottlenecks using the profiler.Using built-in functions that are already vectorized.Matlab code and output illustrated in the following table. And ( 1:3 ) ’ represents numbers from 1 to 3 (1, 2, 3) in a vertical manner. 1:3 represents numbers from 1 to 3 (1, 2, 3) in a horizontal manner. In this type input is a range of numbers. Matlab EditorĪrray name = (range) and array name = (range) ’ Example #5: Horizontal & Vertical Implementation Here arr is the name of the array, one is the number of rows,3 is the number of columns and two is the repetition of the output matrix. If we want output block multiple times then we can use this command. Repmat(arr,) Example #4: Matlab implementation Here the number of rows is five and the numbers of columns are 2. In previous example dimensions of the matrix were restrict but in this example, we can give the number of rows and number of columns separately. Repmat (array name, no of rows, no of columns) Example #3: Matlab implementation Matlab code and output script illustrated in the following table. this command produces an output of two rows and two columns. here we declare the elements of the array we can add any elements into the array. In this type arr is the name of any array. Repmat (array name, number of rows and columns)
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