The expression A(A > 5) is equivalent to A(find(A > 5)). Logical indexing is closely related to the find function. Or you could replace all the spaces in a string matrix str with underscores. To replace all NaN elements of the matrix B with zero, use B(isnan(B)) = 0 For example, you could replace all the NaN elements in an array with another value by using a combination of isnan, logical indexing, and scalar expansion. Many MATLAB functions that start with is return logical arrays and are very useful for logical indexing. For example, A(A > 12) extracts all the elements of A that are greater than 12. The output is always in the form of a column vector. MATLAB extracts the matrix elements corresponding to the nonzero values of the logical array. In logical indexing, you use a single, logical array for the matrix subscript. This form of indexed assignment is called scalar expansion.Īnother indexing variation, logical indexing, has proven to be both useful and expressive. You can always, however, use a scalar on the right side: v() = 30 % Replace second and third elements by 30 Usually the number of elements on the right must be the same as the number of elements referred to by the indexing expression on the left. V(end:-1:1) % Reverse the order of elementsīy using an indexing expression on the left side of the equal sign, you can replace certain elements of the vector: v() = % Replace some elements of v You can even do arithmetic using end: v(2:end-1) % Extract the second through the next-to-last elementsĬombine the colon operator and end to achieve a variety of effects, such as extracting every k-th element or flipping the entire vector: v(1:2:end) % Extract all the odd elements The end operator can be used in a range: v(5:end) % Extract the fifth through the last elements The special end operator is an easy shorthand way to refer to the last element of v: v(end) % Extract the last element Swap the two halves of v to make a new vector: v2 = v() % Extract and swap the halves of v The colon notation in MATLAB provides an easy way to extract a range of elements from v: v(3:7) % Extract the third through the seventh elements Or the subscript can itself be another vector: v() % Extract the first, fifth, and sixth elements The subscript can be a single value: v(3) % Extract the third element When you're ready, you can load the file into the platform.Let's start with the simple case of a vector and a single subscript. mat extension or a MAT file if you use it for several sessions. You must save the data as a compressed file with a. You'll be able to see the code cell by cell this way. csv file if you need to arrange the code. This file format can also handle two-dimensional matrices and character strings, multidimensional numeric arrays, and 64-bit floating points, among other things. Since MAT files are binary data containers that contain variables, functions, arrays, and other codes, they are more complex than M-files. mat format to handle more diverse codes and make it more available to other programs. This indicates that it will fulfill the prompt's series. When you open this file, the platform will read the commands for you and execute them exactly as you typed them. All of your MATLAB commands are stored in the M-file, which is a plain text file. The native file extensions for MATLAB are. It's worth noting that variables aren't saved by default. It has variables that you've generated or that you've imported from other systems. You will get the code for your command line from the workspace. You can also delete the default toolbar from the menu bar, allowing you to display the interface as a single command line. The command window is the most critical of the four. The command window, workspace, navigation toolbox, and toolstrip are the four parts of MATLAB's homepage. Wait for the K> prompt to appear after clicking the Debug key on the menu bar.Īlthough its extensive feature set delays computation speed, you will find that its graphical user interface is more straightforward and well-organized than that of other platforms such as C++ or Fortran. In the command window, you can also debug M-files. The > symbol means that the program can handle the variables' values. Two right-facing double-angle quotation marks are used to denote the prompt. You'll enter results, execute functions, and open other MATLAB files in the MATLAB command window.
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