Warning: Matrix is singular to working precision.Ĭomponent-wise Operations Multiplication and division are more problematic: multiplying two vectors in R n. The multiplication by a scalar also works as expected: It then finds and returns all values in the a which are true. The second method is to use logical addressing, which first changes a into a logical array, with value 1 if the logical expression is true and 0 if it is false. The first is to use the find function to find the indices of all numbers between 2 and 4 in the array, and then address the array with those indices: For example, suppose a = and you only want the values between 2 and 4. In addition to index addressing, you can also access only elements of an array that satisfy some logical criterion. > a(1, 2:end) %row 1, columns from 2 until end of the array Using the end Operator įinally, if you do not know the size of an array but wish to access all elements from a certain index until the end of the array, use the end operator, as in The syntax a(:) changes a into a column vector (column major): Now say you only want the first two elements in the first row. For example, say you want to access the entire first row of matrix a above, but not the second row. This operator is like a wildcard it tells MATLAB that you want all elements of a given dimension or with indices between two given values. It is also possible to access blocks of matrices using the colon (:) operator. The column major mode is the same as in Fortran, and the contrary You can also access a matrix element through a unique index in this case, the order is column major, meaning you first go throughĪll elements of the first column, then the 2d column, etc.

To access a single matrix element, you can use the (i,j) subscript, where i is the index in the row, and j in the column: Accessing the content of an array is done through the operator (), with the index inside the parenthesis the indexing of the first element is 1:Īccessing an element outside the bounds will result in an error: Now that you know how to define a simple array, you should know how to access its elements. However, there are special functions just for vectors see the vector module for an explanation of how to use these.īasics Accessing elements of a matrix Using a Single Index In MATLAB, both are arrays of doubles (thus being a matrix in the real mathematical meaning), and MATLAB considers vectors as a matrices with only one row or only one column. However, we won't be as precise as in mathematics when using the terms vector and matrix. See the previous section for that.Īrrays in MATLAB obey the same rule as their mathematical counterpart: by default, the matrix definitions of operations are used, unless a special operator called the dot operator is applied.īecause arrays operations are so similar to the equivalent mathematical operations, a basic knowledge of linear algebra is mandatory to use matlab effectively.

Introduction to array operations Īs arrays are the basic data structure in MATLAB, it is important to understand how to use them effectively. 2.1.4 Using a Colon (:) for a Block Index.Fundamentals of MATLAB MATLAB Workspace MATLAB Variables *.mat filesĬhapter 2: MATLAB Concepts MATLAB operator Data File I/OĬhapter 3: Variable Manipulation Numbers and Booleans Strings Portable Functions Complex NumbersĬhapter 4: Vector and matrices Vector and Matrices Special Matrices Operation on Vectors Operation on Matrices Sparse MatricesĬhapter 5: Array Arrays Introduction to array operations Vectors and Basic Vector Operations Mathematics with Vectors and Matrices Struct Arrays Cell ArraysĬhapter 6: Graphical Plotting Basic Graphics Commands Plot Polar Plot Semilogx or Semilogy Loglog Bode Plot Nichols Plot Nyquist PlotĬhapter 7: M File Programming Scripts Comments The Input Function Control Flow Loops and Branches Error Messages Debugging M FilesĬhapter 8: Advanced Topics Numerical Manipulation Advanced File I/O Object Oriented Programming Applications and Examples Toolboxes and ExtensionsĬhapter 9: Bonus chapters MATLAB Benefits and Caveats Alternatives to MATLAB Octave/MATLAB differences

Matlab access matrix by vector