MATLAB: Converting these mathematical formulas to a matlab equation.

mathematical formulas

How can i convert these to a proper matlab equation?

v0=25;
theta1= 30;
y0=3.5;
d1=(v0.*cos(theta1).*(v0.*sin(theta1)+ sqrt((v0.*sin(theta1)).^2 + 2.*9.81.*y0)))/9.81
y1=(x1.*tan(theta1))-((1/2).*((9.81.*(x1)^.2)/((v0.*cos(theta1))^.2))) +y0
But

I spend a lot of time to write it but it doesn't work. Thank you.

Best Answer

(x1)^.2

You probably didn't mean to raise a square matrix x1 to the 0.2 power here for two reasons.

By the way, cos isn't quite the correct function to use. It computes the cosine of an angle in radians. But the "See Also" section on its documentation page (doc cos) lists the correct function to use for your problem.

Related Solutions

MATLAB: Strange behavior of diff function with symbolic variables

Hi,

Your expression, D contains only 2 theta1 terms(in bold) whose derivatives cancel each other. Differentiation of theta2 and theta3 wrt theta1 is zero. Therefore your answer is zero.

D =0.31*cos(theta1)^2 - 2.7e-4*sin(theta2) - 0.88*sin(theta2)*(7.3e-5*cos(theta2) - 0.011*sin(theta2) + 3.1e-4) - 0.88*cos(theta2)*(7.3e-5*sin(theta2) - 4.2e-3*cos(theta2) + 4.6e-4) - 1.0*(0.48*sin(theta3) - 0.88*cos(theta2)*cos(theta3))*(5.1e-4*cos(theta3) - 1.7e-4*sin(theta2) - 0.047*sin(theta3) + 0.088*cos(theta2)*cos(theta3) + 9.5e-4*cos(theta2)*sin(theta3)) - 4.1e-4*cos(theta2) + 0.88*sin(theta2)*(3.2e-4*cos(theta3) + 0.073*sin(theta2) + 9.0e-5*sin(theta3) - 1.7e-4*cos(theta2)*cos(theta3) + 5.9e-4*cos(theta2)*sin(theta3)) + 0.31*sin(theta1)^2 + 1.0*(0.48*cos(theta3) + 0.88*cos(theta2)*sin(theta3))*(0.035*cos(theta3) + 5.9e-4*sin(theta2) - 5.1e-4*sin(theta3) + 9.5e-4*cos(theta2)*cos(theta3) + 0.064*cos(theta2)*sin(theta3)) + 0.33;

I hope I could help.

Regards

MATLAB: How can i fix this ode45 error: Not enough input arguments.

Try this:

syms x1 x2 t 
x1_dot = (6*atan((53*x1)/9))/(25*pi) - 40*x1 + (6*atan((179*x2)/18))/(25*pi);
x2_dot = (6*atan((53*x1)/9))/(25*pi) - 40*x1 + (6*atan((179*x1)/18))/(25*pi);
x_dot_num = matlabFunction([x1_dot; x2_dot], 'Vars', {t, [x1 x2]});
% x2_dot_num=matlabFunction(x2_dot, 'Vars', {'t', 'x1','x2'});
x1_0 = 4; 
x2_0 = 5;
ic = [x1_0 x2_0];
tspan = [0 3];
[t,x_dot_sol] = ode45(@(t,in2)x_dot_num(t,in2.'),tspan,[x1_0 x2_0]);
% [t,x2_dot_sol] = ode45(x2_dot_num,tspan,x1_0);
figure
plot(t, x_dot_sol)
grid

The ‘[x1 x2]’ vectoir in the 'Vars' argument creates them as a parameter set, however it defines them as a row vector. Since the MATLAB ODE solvers want them as a column vector, this call to ‘x_dot_num’:

@(t,in2)x_dot_num(t,in2.')

(note the transpose of ‘in2’) in the ode45 call corrects for that.

This code runs without error. (I left the commented-out lines in so you can understand the changes.)

Best Answer

Related Solutions

MATLAB: Strange behavior of diff function with symbolic variables

MATLAB: How can i fix this ode45 error: Not enough input arguments.

Related Question