MATLAB Conversion from classical orbital elements into RV.

coe2rv.m

function [r,v] = coe2rv(a, e, inc, raan, argp, theta, mu)
    cos_raan = cos(raan);
    sin_raan = sin(raan);
    cos_argp = cos(argp);
    sin_argp = sin(argp);
    cos_inc = cos(inc);
    sin_inc = sin(inc);
    r = a * (1 - e ^ 2) / (1.0 + e * cos(theta));

    l1 = (+cos_raan * cos_argp - sin_raan * sin_argp * cos_inc);
    l2 = (-cos_raan * sin_argp - sin_raan * cos_argp * cos_inc);
    m1 = (+sin_raan * cos_argp + cos_raan * sin_argp * cos_inc);
    m2 = (-sin_raan * sin_argp + cos_raan * cos_argp * cos_inc);
    n1 = sin_argp * sin_inc;
    n2 = cos_argp * sin_inc;

    aux = [r * cos(theta); r * sin(theta)];
    transformation = [l1, l2;...
                      m1, m2;...
                      n1, n2];

    % Position
    xyz = transformation * aux;
    x = xyz(1);
    y = xyz(2);
    z = xyz(3);

    % Velocity
    H = sqrt(mu * a * (1 - e ^ 2));
    v_x = mu / H * (-l1 * sin(theta) + l2 * (e + cos(theta)));
    v_y = mu / H * (-m1 * sin(theta) + m2 * (e + cos(theta)));
    v_z = mu / H * (-n1 * sin(theta) + n2 * (e + cos(theta)));
    r = [x, y, z];
    v = [v_x, v_y, v_z];
end