Wiered Matlab Matrix Multiplication

 t = linspace(0, 1, 100);
    theta1 = linspace(0, 90, 100);
    theta2 = linspace(0, 180, 100);
    dtheta1 = t;
    dtheta2 = 2*t;
    ddtheta1 = 1;
    ddtheta2 = 2;
    T1 = zeros(100,1);
        T2 = zeros(100,1);
    m_1 = 10;
    m_2 = 20;
    l_1 = 5;
    l_2 = 5;
    g = 9.81;
    
    for i = 1:100
      M = [m_2*l_2^2 + 2*m_2*l_1*l_2*cos(theta2(i)) + (m_1 + m_2)*l_1^2, m_2*l_2^2 + m_2*l_1*l_2*cos(theta2(i)); 
        m_2*l_2^2 + m_2*l_1*l_2*cos(theta2(i)), m_2*l_2^2 ];

  %  invM = inv(M);     

    G = [m_2*l_2*g*cos(theta1(i) + theta2(i)) + (m_1 + m_2)*l_1*g*cos(theta1(i)); m_2*l_2*g*cos(theta1(i) + theta2(i))];

    C = [-m_2*l_1*l_2*sin(theta2(i))*dtheta1(i)^2 - 2*m_2*l_1*l_2*sin(theta2(i))*dtheta1(i)*dtheta2(i); m_2*l_1*l_2*sin(theta2(i))*dtheta1(i)^2];

      
        M*[ddtheta1; ddtheta2] + C + G
  end

I don't know why the last statement sometimes prints 2*1 but sometimes give something like this:

   ans =
   1.0e+03 *

    5.2709
    2.9356

Any suggestion where is this e terms coming from?

FYI: M is 2*2, G = 2*1, C = 2*1 matrices;

[Roger Stafford]

The variables theta1 and theta2 are clearly meant to be in degrees, but you are using them as arguments for Matlab's 'cos' and 'sin' functions, which are intended to receive arguments in radians. That will give you a serious computation error.

[Sonu Patidar]

Yes, thanks for pointing out that.

Answer 1

[KL]

it is coming from

 M*[ddtheta1; ddtheta2] + C + G

if you do not put a semicolon on matlab, you'll see the output of that line on command window.

https://de.mathworks.com/help/matlab/matlab_prog/matlab-operators-and-special-characters.html

[Sonu Patidar]

No, I was asking where that extra term 1.0e+03 * coming from? Anyway I got it. We need to convert floating point representation to uint64.

[KL]

e stands for exponent

[John D'Errico]

Exponential notation.

[Sonu Patidar]

Yes, you are right.