#include <iostream> #include "armadillo" using namespace arma; using namespace std; int main(int argc, char** argv) { cout << "Armadillo version: " << arma_version::as_string() << endl; // directly specify the matrix size (elements are uninitialised) mat A(2,3); // .n_rows = number of rows (read only) // .n_cols = number of columns (read only) cout << "A.n_rows = " << A.n_rows << endl; cout << "A.n_cols = " << A.n_cols << endl; // directly access an element (indexing starts at 0) A(1,2) = 456.0; A.print("A:"); // scalars are treated as a 1x1 matrix, // hence the code below will set A to have a size of 1x1 A = 5.0; A.print("A:"); // if you want a matrix with all elements set to a particular value // the .fill() member function can be used A.set_size(3,3); A.fill(5.0); A.print("A:"); mat B; // endr indicates "end of row" B << 0.555950 << 0.274690 << 0.540605 << 0.798938 << endr << 0.108929 << 0.830123 << 0.891726 << 0.895283 << endr << 0.948014 << 0.973234 << 0.216504 << 0.883152 << endr << 0.023787 << 0.675382 << 0.231751 << 0.450332 << endr; // print to the cout stream // with an optional string before the contents of the matrix B.print("B:"); // the << operator can also be used to print the matrix // to an arbitrary stream (cout in this case) cout << "B:" << endl << B << endl; // save to disk B.save("B.txt", raw_ascii); // load from disk mat C; C.load("B.txt"); C += 2.0 * B; C.print("C:"); // submatrix types: // // .submat(first_row, first_column, last_row, last_column) // .row(row_number) // .col(column_number) // .cols(first_column, last_column) // .rows(first_row, last_row) cout << "C.submat(0,0,3,1) =" << endl; cout << C.submat(0,0,3,1) << endl; // generate the identity matrix mat D = eye<mat>(4,4); D.submat(0,0,3,1) = C.cols(1,2); D.print("D:"); // transpose cout << "trans(B) =" << endl; cout << trans(B) << endl; // maximum from each column (traverse along rows) cout << "max(B) =" << endl; cout << max(B) << endl; // maximum from each row (traverse along columns) cout << "max(B,1) =" << endl; cout << max(B,1) << endl; // maximum value in B cout << "max(max(B)) = " << max(max(B)) << endl; // sum of each column (traverse along rows) cout << "sum(B) =" << endl; cout << sum(B) << endl; // sum of each row (traverse along columns) cout << "sum(B,1) =" << endl; cout << sum(B,1) << endl; // sum of all elements cout << "sum(sum(B)) = " << sum(sum(B)) << endl; cout << "accu(B) = " << accu(B) << endl; // trace = sum along diagonal cout << "trace(B) = " << trace(B) << endl; // random matrix -- values are uniformly distributed in the [0,1] interval mat E = randu<mat>(4,4); E.print("E:"); cout << endl; // row vectors are treated like a matrix with one row rowvec r; r << 0.59499 << 0.88807 << 0.88532 << 0.19968; r.print("r:"); // column vectors are treated like a matrix with one column colvec q; q << 0.81114 << 0.06256 << 0.95989 << 0.73628; q.print("q:"); // dot or inner product cout << "as_scalar(r*q) = " << as_scalar(r*q) << endl; // outer product cout << "q*r =" << endl; cout << q*r << endl; // multiply-and-accumulate operation // (no temporary matrices are created) cout << "accu(B % C) = " << accu(B % C) << endl; // sum of three matrices (no temporary matrices are created) mat F = B + C + D; F.print("F:"); // imat specifies an integer matrix imat AA; imat BB; AA << 1 << 2 << 3 << endr << 4 << 5 << 6 << endr << 7 << 8 << 9; BB << 3 << 2 << 1 << endr << 6 << 5 << 4 << endr << 9 << 8 << 7; // comparison of matrices (element-wise) // output of a relational operator is a umat umat ZZ = (AA >= BB); ZZ.print("ZZ ="); // 2D field of arbitrary length row vectors // (fields can also store abitrary objects, e.g. instances of std::string) field<rowvec> xyz(3,2); xyz(0,0) = randu(1,2); xyz(1,0) = randu(1,3); xyz(2,0) = randu(1,4); xyz(0,1) = randu(1,5); xyz(1,1) = randu(1,6); xyz(2,1) = randu(1,7); cout << "xyz:" << endl; cout << xyz << endl; // cubes ("3D matrices") cube Q( B.n_rows, B.n_cols, 2 ); Q.slice(0) = B; Q.slice(1) = 2.0 * B; Q.print("Q:"); return 0; }