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 Here we discuss the introduction, formation and operations on matrix respectively.Let's start with the simple case of a vector and a single subscript. All the operations can be easily performed in MatLab, such as addition, multiplication, subtraction, trigonometric functions, cross multiplication, matrix transpose, matrix inverse, complex numbers, etc. MatLab makes it simple, and MatLab is specially designed for matrix manipulations. In matrix arithmetic, addition and subtraction are easy, but multiplication is a challenging task. Screen 8: Size of Matrix Conclusion – Matrix in Matlab Here 3 represents no of rows, and 4 represents no of columns. It gives the size in the form of rows and columns. This command is used to find the size of the matrix. The above example is illustrated on screen 7: It is a two by-two matrix the output will be: Here 0 is the real part, and 1 is an imaginary part.Ĭomplex numbers representation is as follows: If we put square root operation in MatLab command window ( sqrt ( -1 ) ) then it gives output as 0.0000 + 1.0000 i. Real parts and imaginary parts are generally used to represent imaginary parts ‘ I ’ and ‘ j ’ variables. Inside the brackets, 4 means four rows, and 1 is a number of a column.Ī=ones(2,3) … … … Two rows and three columns.Ĭoncatenation is used to join two matrices, and square brackets are used for the concatenation operator.Ĭomplex numbers are a mixture of two parts.Another way to create a matrix is by using the commands zeros, ones, etc. Screen 1 shows the formation of a matrix that illustrates the above example.In this elements are written in square brackets ( ‘ ’ ) and each row is separated by a semicolon ( ‘ ’ ).To create the above matrix in MatLab, commands will be: To create a matrix, we need to specify a two-dimensional array let us consider one example Matrix A is An array is a one-dimensional quantity.In the above example, there are four elements in one row.An array is a row vector, so to create array commands will be X = First, we will see how to create an array in Matlab.Hadoop, Data Science, Statistics & others Matrix Formation
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