I need my code to output in both numerical form and symbolical form.

Hello MATLAB Community,

Here is my code:

syms phi theta psi 

mobile = 110.75; 

d2r = pi/180;
r2d = 180/pi;

phi = 5*d2r;
theta = 10*d2r;

if phi >= 0
    psi = -phi ; 
elseif phi1 <= 0
    psi = -phi ;  
end

ROT = [(cos(phi)*cos(psi))-(cos(theta)*sin(phi)*sin(psi)) -(cos(phi)*sin(psi))-(cos(theta)*cos(psi)*sin(phi)) (sin(phi)*sin(theta));...
    (cos(psi)*sin(phi))+(cos(phi)*cos(theta)*sin(psi)) (cos(phi)*cos(theta)*cos(psi)-sin(phi)*sin(psi)) -(cos(phi)*sin(theta));...
    (sin(theta)*sin(psi)) (cos(psi)*sin(theta)) cos(theta)];

x = (mobile/2)*(ROT(1,1)-ROT(2,2))
y = -mobile*ROT(2,1)

So, when you run this code, you get results of x & y in numerical form.

I want my code to output in two forms numerical and in symbolical (in terms keeping x & y as equations).

I tried some ways to achieve it and after verification I saw that the numerical answer won't match the solutions of the equations generated.

When my x & y are in equation form, I can use these equations for differentiation in the later part of my code.

Can anyone please help me with this,

Thank you,

Shiv

Answer 1

[Dyuman Joshi]

Define and substitute the values after obtaining the required result in symbolic form -

syms phi theta psi 

mobile = 110.75; 

d2r = pi/180;
r2d = 180/pi;

ROT = [(cos(phi)*cos(psi))-(cos(theta)*sin(phi)*sin(psi)) -(cos(phi)*sin(psi))-(cos(theta)*cos(psi)*sin(phi)) (sin(phi)*sin(theta));...
    (cos(psi)*sin(phi))+(cos(phi)*cos(theta)*sin(psi)) (cos(phi)*cos(theta)*cos(psi)-sin(phi)*sin(psi)) -(cos(phi)*sin(theta));...
    (sin(theta)*sin(psi)) (cos(psi)*sin(theta)) cos(theta)];

%symbolic expressions
x_sym = (mobile/2)*(ROT(1,1)-ROT(2,2))

x_sym = 

y_sym = -mobile*ROT(2,1)

y_sym = 

phi0 = 5*d2r;
theta0 = 10*d2r;
psi0 = -phi0;

%numeric values
x_num = double(subs(x_sym,[phi theta psi], [phi0 theta0 psi0]))

x_num = 0.8285

y_num = double(subs(y_sym,[phi theta psi], [phi0 theta0 psi0]))

y_num = -0.1461

[Shiv Karpoor]

Thank you Dyuman Joshi.