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[top] API Documentation for Armadillo 15.6


Preamble

For converting Matlab/Octave programs, see the syntax conversion table First time users: please see the short example program If you discover any bugs or regressions, please report them History of API additions

Please cite the following papers if you use Armadillo in your research and/or software. Citations are useful for the continued development and maintenance of the library. Conrad Sanderson and Ryan Curtin. Armadillo: An Efficient Framework for Numerical Linear Algebra. International Conference on Computer and Automation Engineering, 2025. Conrad Sanderson and Ryan Curtin. Practical Sparse Matrices in C++ with Hybrid Storage and Template-Based Expression Optimisation. Mathematical and Computational Applications, Vol. 24, No. 3, 2019.

Overview

• matrix, vector, cube and field classes
• member functions & variables


• generated vectors / matrices / cubes
• functions of vectors / matrices / cubes


• decompositions, factorisations, inverses and equation solvers (dense matrices)
• decompositions, factorisations, and equation solvers (sparse matrices)


• signal & image processing
• statistics and clustering
• miscellaneous (constants, configuration options, ...)

Matrix, Vector, Cube and Field Classes

Mat<type>, mat, cx_mat		dense matrix class
Col<type>, colvec, vec		dense column vector class
Row<type>, rowvec		dense row vector class
Cube<type>, cube, cx_cube		dense cube class (quasi third-order tensor, aka "3D matrix")
field<object type>		class for storing arbitrary objects in matrix-like or cube-like layouts
SpMat<type>, sp_mat, sp_cx_mat		sparse matrix class
operators		+  −  *  %  /  ==  !=  <=  >=  <  >  &&  ||

Member Functions & Variables

attributes		.n_rows, .n_cols, .n_elem, .n_slices, ...
element access		element/object access via (), [] and .at()
element initialisation		set elements via initialiser lists
.zeros		set all elements to zero
.ones		set all elements to one
.eye		set elements along main diagonal to one and off-diagonal elements to zero
.randu / .randn		set all elements to random values
.fill		set all elements to specified value
.imbue		imbue (fill) with values provided by functor or lambda function
.push_back		append elements to vectors
.clean		replace elements below a threshold with zeros
.replace		replace specific elements with a new value
.clamp		clamp values to lower and upper limits
.transform		transform each element via functor or lambda function
.for_each		apply a functor or lambda function to each element
.set_size		change size without keeping elements (fast)
.reshape		change size while keeping elements
.resize		change size while keeping elements and preserving layout
.copy_size		change size to be same as given object
.reset		change size to empty
submatrix views		read/write access to contiguous and non-contiguous submatrices
subcube views		read/write access to contiguous and non-contiguous subcubes
subfield views		read/write access to contiguous subfields
.diag		read/write access to matrix diagonals
.each_col / .each_row		vector operations applied to each column/row of matrix (aka "broadcasting")
.each_slice		matrix operations applied to each slice of cube (aka "broadcasting")
.set_imag / .set_real		set imaginary/real part
.insert_rows / cols / slices		insert vector / matrix / cube at specified row/column/slice
.shed_rows / cols / slices		remove specified rows/columns/slices
.swap_rows / cols		swap specified rows or columns
.swap		swap contents with given object
.memptr		raw pointer to memory
.colptr		raw pointer to memory used by specified column
iterators (matrices)		iterators and associated member functions for dense matrices and vectors
iterators (cubes)		iterators and associated member functions for cubes
iterators (sparse matrices)		iterators and associated member functions for sparse matrices
iterators (submatrices)		iterators and associated member functions for submatrices & subcubes
compat. container functions		compatibility container functions
.as_col / .as_row		return flattened matrix as column or row vector
.col_as_mat / .row_as_mat		return matrix representation of cube column or cube row
.as_dense		return dense vector / matrix  representation of sparse matrix expression
.t / .st		return matrix transpose
.i		return inverse of square matrix
.min / .max		return extremum value
.index_min / .index_max		return index of extremum value
.eval		force evaluation of delayed expression
.in_range		check whether given location or span is valid
.is_empty		check whether object is empty
.is_vec		check whether matrix is a vector
.is_sorted		check whether vector or matrix is sorted
.is_trimatu / .is_trimatl		check whether matrix is upper/lower triangular
.is_diagmat		check whether matrix is diagonal
.is_square		check whether matrix is square sized
.is_symmetric		check whether matrix is symmetric
.is_hermitian		check whether matrix is hermitian
.is_sympd		check whether matrix is symmetric / hermitian positive definite
.is_zero		check whether all elements are zero
.is_finite		check whether all elements are finite
.has_inf		check whether any element is ±infinity
.has_nan		check whether any element is NaN
.print		print object to std::cout or user specified stream
.raw_print		print object without formatting
.brief_print		print object in shortened/abridged form