How to insert variables (string) in MATLAB function

Question

Pk Verma 2021-10-25

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1570973-how-to-insert-variables-string-in-matlab-function

评论： Pk Verma 2021-10-25

function R=rotmatx(axis,q)
if axis=='x'    
    R=[1 0 0;0 cos(q) -sin(q); 0 sin(q) cos(q)];
elseif axis=='y'
    R=[cos(q) 0 sin(q); 0 1 0; -sin(q) 0 cos(q)];
elseif axis=='z'
    R=[cos(q) -sin(q) 0;-sin(q) cos(q) 0; 0 0 1];
else
    fprintf('invalid axis');
end 

so, i want the output when i call this function

rotmatx('x','t')

the output should be

[1, 0, 0]

[0, cos(t), -sin(t)]

[0, sin(t), cos(t)]

but there is error.

Can someone please help me out for this.

Thank You.

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Answer 1

Walter Roberson 2021-10-25

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1570973-how-to-insert-variables-string-in-matlab-function#answer_816118

在 MATLAB Online 中打开

rotmatx('y', 'p')

ans =

rotmatx('z', pi/6)

ans =

function R=rotmatx(axis,q)

Q = sym(q);

if axis=='x'

R=[1 0 0;0 cos(Q) -sin(Q); 0 sin(Q) cos(Q)];

elseif axis=='y'

R=[cos(Q) 0 sin(Q); 0 1 0; -sin(Q) 0 cos(Q)];

elseif axis=='z'

R=[cos(Q) -sin(Q) 0;-sin(Q) cos(Q) 0; 0 0 1];

else

fprintf('invalid axis');

end

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Pk Verma 2021-10-25

Thank you sir.

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Answer 2

KSSV 2021-10-25

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1570973-how-to-insert-variables-string-in-matlab-function#answer_815668

编辑：KSSV 2021-10-25

在 MATLAB Online 中打开

syms t

R=[1 0 0;0 cos(t) -sin(t); 0 sin(t) cos(t)]

R =

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KSSV 2021-10-25

You can follow the above method and write into a function.

Pk Verma 2021-10-25

在 MATLAB Online 中打开

Do you mean this

function R=tst(t)
syms t
R=[1 0 0;0 cos(t) -sin(t); 0 sin(t) cos(t)];
end 

now

tst('p')

now output is...

[1, 0, 0]

[0, cos(t), -sin(t)]

[0, sin(t), cos(t)]

but output should be

[1, 0, 0]

[0, cos(p), -sin(p)]

[0, sin(p), cos(p)]

if i done anything wrong then please write function and then function calling code.

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