To create:

f[]@myFarray = {0,1,2,3,4,5,6};
i[]@myIarray = {0,1,2,3,4,5,6};
v[]@myVarray = {{1,2,3},{4,5,6}};
v@readvect = @myVarray[1];

3[]@myMatrixarray = { {0,0,0,0,0,0,0,0,0}, {0,0,0,0,0,0,0,0,0}};

matrix3 mat = {1,2,3,4,5,6,7,8,9};
3[]@myMatrixarray[0] = mat; //assign

Read from prim:

3[]@rotmatrixarray[index] = prim(0, "rotmatrix", index );

Read from attrib:

vector array[] = v[]@atrail;
vector position = array[i];

Append:

float solve_beats[] = {};
for (int i = 0; i<700; i++)
    {
    if (val_curr >= 0.1) append(solve_beats, i);
    }
    
int lenght = len(solve_beats);

Create empty, resize, faster:

f[]@array;
resize(@array, len);