problem with the symbolic calculation

Hello! i have a problem: I have a peace of code:

Q1=30;
Q1rad=(pi/180)*Q1;
S1= sym('sin(Q1rad)');
double(S1)

and it doesn.t work because I translate variable to the 'sin(...)' how to make it works? what is the way to calculate expressions with "sin(Q1rad)" and in the end substitute the Q1rad, and calculate the final value of the expression?

best regards! Dmytro.

Answer 1

[Azzi Abdelmalek]

I translate variable to the 'sin(...)' , what doesthat mean?

If you want double(S1), just write:

sin(Q1rad)

[Dk]

for example, why I can not compute double(C) here?

syms A B C S1 S2 S3;
A=[S1 S2 1;2 3 S2; 3 S1 S3];
B=[S3 S1 1;3 2 S1; 2 S3 S2];
C=A*B;
Q1=30;Q2=20;Q3=10;
Q1rad=(pi/180)*Q1;
Q2rad=(pi/180)*Q2;
Q3rad=(pi/180)*Q3;
S1=sin(Q1rad)
S2=sin(Q2rad)
S3=sin(Q3rad)
double(C)

[Azzi Abdelmalek]

%Do not put the cart before the horse

syms A B C S1 S2 S3;
Q1=30;Q2=20;Q3=10;
Q1rad=(pi/180)*Q1;
Q2rad=(pi/180)*Q2;
Q3rad=(pi/180)*Q3;
S1=sin(Q1rad)
S2=sin(Q2rad)
S3=sin(Q3rad)
A=[S1 S2 1;2 3 S2; 3 S1 S3];
B=[S3 S1 1;3 2 S1; 2 S3 S2];
C=A*B;
double(C)

[Dk]

:DD sorry maybe my questions are a little stupid, but why I can not compute here double(S1) ? or I should change my approach?

Q1=30;
Q1rad=(pi/180)*Q1;
S1= sym('sin(Q1rad)');
double(S1)

[Azzi Abdelmalek]

Q1=30;
Q1rad=(pi/180)*Q1;
S1= sym('sin(Q1rad)')
double(subs(S1))

[Dk]

YES) Thank you!

Answer 2

[Andrei Bobrov]

q = [30;20;10];
S = sind(q);
A = [S(1) S(2) 1;2 3 S(2);3 S(1) S(3)];
B=[S(3) S(1) 1;3 2 S(1); 2 S(3) S(2)];
C = A*B;