Arrays

1 Declaring Arrays

An array is a collection of variables, which are all of the same type. An array variable can be declared by appending dimensions within square brackets after a class name or after a variable name.

class ArrayDim Real n = 1, m = 4, k = 5; Real Voltage; // 3-dimensional position vector Real[3] positionvector = {1, 2, 3}; // transformation matrix Real[3,3] identitymatrix = {{1, 0, 0}, {0, 1, 0}, {0, 0, 1}}; // A 3-dimensional array Integer[n,m,k] arr3d; // A boolean vector Boolean[2] truthvalues = {false, true}; // A vector of voltage values Voltage[10] voltagevector; end ArrayDim;

Using the alternative syntax of attaching dimensions after the variable name, the same declarations can be expressed as:

class ArrayDim Real n = 1, m = 4, k = 5; Real Voltage; Real positionvector[3] = {1, 2, 3}; Real identitymatrix[3,3] = {{1, 0, 0}, {0, 1, 0}, {0, 0, 1}}; Integer arr3d[n,m,k]; Boolean truthvalues[2] = {false, true}; Voltage voltagevector[10]; end ArrayDim;

2 Multiplication Operator

The multiplication operator * is scalar product when used between vectors, matrix multiplication when used between matrices and element-wise multiplication when used between an array and a scalar. In the function ElementWiseMultiplication positionvector is multiplied by the scalar 2.

function ElementWiseMultiplication input Real[3] positionvector; output Real[3] result; algorithm result := positionvector*2; end ElementWiseMultiplication;

3 Calling ElementWiseMultiplication

We see that when applying the function ElementWiseMultiplication on positionvector, we get the result {2, 4, 6}.

ElementWiseMultiplication({1, 2, 3})

4 Matrix Declaration

The common special cases of concatenation along the first and second dimensions are supported through the special syntax forms [A;B;C;...] and [A,B,C,...] respectively. Both of these forms can be mixed. Scalar and vector arguments to these special operators are promoted to become matrices before performing the concatenation. This gives the effect that a matrix can be constructed from scalar expressions by separating rows by semicolon and columns by comma.

class Matrix Real matrix[2, 2] = [1, 2; 3, 4]; end Matrix;