Why the numerical values for function handle from matlabFunction should be written one by one?

Hi guys,

I am now using matlabFunction for change a symbolic expression into a funtion handle.

I find a question like this: if I write the numeric values one by one to replace the symbolic variables like this:

then the answer can be obtained as 3.

However, if I write

F2= f( aa )

then, in the command window, it shows like this:

Could anyone help me about this question?

Thanks so much!

[Stephen23]

What exactly is the problem?

Three scalar input arguments are not the same as a three-element vector input argument.

[Tony Cheng]

Hi Stephen,

Thanks so much for your reply!

I mean, the arguments cannot be input into the function handle in a vertor manner, but they are input as scalars. The number of variables in the problem is big, then we have to write the scalars one by one like this :

F2 = f( aa(1) , aa(2) , aa(3) , aa(4) , aa(5) , aa(6) , aa(7) , aa(8) , aa(9) , aa(10) , aa(11) , aa(12) , aa(13) , aa(14) , aa(15) , aa(16) , aa(17) , aa(18) , aa(19) , aa(20) , aa(21) , aa(22) ) ;

Are there any methods to write them in a more compact way?

Cheers

Answer 1

[madhan ravi]

Because your function requires three inputs but you fed in 1

f(aa(1),aa(2),aa(3)) 

[Tony Cheng]

Hi madhan,

Thanks so much for your reply!

I mean, the arguments cannot be input into the function handle in a vertor manner, but they are input as scalars. The number of variables in the problem is big, then we have to write the scalars one by one like this :

F2 = f( aa(1) , aa(2) , aa(3) , aa(4) , aa(5) , aa(6) , aa(7) , aa(8) , aa(9) , aa(10) , aa(11) , aa(12) , aa(13) , aa(14) , aa(15) , aa(16) , aa(17) , aa(18) , aa(19) , aa(20) , aa(21) , aa(22) ) ;

Are there any methods to write them in a more compact way?

Cheers

[madhan ravi]

well then see

https://www.mathworks.com/matlabcentral/answers/48928-converting-a-vector-to-multiple-variables-required-as-input-for-matlabfunction#answer_59789

[Walter Roberson]

Yes using vars is the way to go. Pass aa cell array as vars and within the cell array each vector of variable names will be bunched together into aa single argument .

[Tony Cheng]

Dear Madhan,

Many thanks Madhan for the fast and efficient reply!

I think it must be an answer! I will try later when connecting to the PC with matlab!

It is really an amazing charm working in that way!

Cheers

[Tony Cheng]

Dear Walter,

Yeah you are rite!

I will do that as shown in https://www.mathworks.com/matlabcentral/answers/48928-converting-a-vector-to-multiple-variables-required-as-input-for-matlabfunction#answer_59789.

it really helps a lot to save time !

Cheers

[madhan ravi]

Anytime :) , if you got the answer to your question make sure to accept the answer.