With a for-loop (file name is mpr_long.GNU Octave is both a programming language and a command-line language interpreter. We are programming the midpoint rule from the previous section Loops and function calls, especially through feval, have a Now the function gauss can be integrated by calling: We define two functions, gauss.m and mpr.m, as eval(string) evaluates string as OctaveĪpproximate an integral by the midpoint rule:.The syntax of for- and while-loops is immediate from the If you change N within the function, it changes in the Global N % makes local N refer to the global N Global N % makes N a global variable may be set in main file Global name declares name as a global variable. Out2 would not have been affected by calling Obviously, the variables out1 and out2 were local toĭolittle. Restriction should also be applied to programs written in Octave.Ī function dolittle, which is saved in the file named

If compatibility with Matlab is important, this m file, where the name of the function must match the name Matlab on the other hand, strictly enforces one function per In Octave, several functions can be defined in a single script file. Local-they do not influence variables defined previously.Ī function f, saved in the file named f.m. With arguments, and all variables used within the function are In contrast to scripts, functions can be called Traditionally, functions are also stored in plain text files with any(A) applies any to each of the columns of.= find(A) finds the indices of all nonzeroĮlements of A.cond(A) computes the condition number ofĪ lot of these commands support further options.S = svd(A) computes the singular values of.Octave:1> A = v = Ģ.7 Inverses, decompositions, eigenvalues A(:,j) = cv assigns to the j-th column of.diag(v,k) generates a matrix with the elements from the.diag(v) generates a matrix with the elements from the.diag(A) creates a column vector containing the diagonal.= size(A) returns the number of rows and.length(v) returns the number of elements of the vector.Octave:2> A^2 % Proper matrix power: A^2 = A*A While * refers to the usual matrix multiplication, rand(m,n) generates a random matrix whose entries are.zeros(m,n) generates the zero matrix of dimension.eye(m,n) produces a matrix with ones on the main.There are functions to create frequently used Automatic generation of vectors with constant increment:.Matrices and vectors are the most important building blocks for Octave:1> x12 = 1/8, long_name = 'A String'Īnd here is a script doless, saved in a file named type name displays information about the variable or.Is given, all variables and functions will be cleared. clear name clears name from memory if no name.whos shows all user-defined variables and functions.When debugging user-defined objects, the following commands are Octave has all the usual mathematical functions +,.varname = expression assigns the result of.at the end of the line denotes that an expression , separates two commands without suppressing on-screen.Terminated by does not display its result on-screen. separates several commands within a line.If their content was typed in line by line. TheyĪre imported by calling the file name without the suffix and behave as Scripts are plain text files with file suffix.All commands can be typed in at the prompt or read from a.help name further explains the variable or function.help lists the names of all built-in functions and.Matlab, beingĬommercial software, has a larger function set, and so the reverseĭoes not always work, especially when the program makes use of Program usually runs unmodified on Matlab. The syntax of Octave resembles that of Matlab. Interface to many standard libraries of numerical mathematics, e.g. Octave is an interactive programming language specifically suitedįor vectorizable numerical calculations. 5.6 Least square fit of a straight line.5.3 Stability functions of BDF-integrators.2.7 Inverses, decompositions, eigenvalues.2.6 Solving linear systems of equations.

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