undefine function or variable

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marwa marwan
marwa marwan 2015-6-24
编辑： Walter Roberson 2015-6-25
ihave a vector positionsa with 20 elements and a variable Alpha_posa and a want to take th ith elemet but this error will kill me
??? Undefined function or method 'Positionsa'
for input arguments of type 'double'.
Error in ==> Untitled at 69
Alpha_posa=Positionsa(i);

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Brendan Hamm
Brendan Hamm 2015-6-24
Judging by what you have written and the error given it seems that your issue is with the capitalization. MATLAB is case sensitive and therefore you would want:
Alpha_posa = positionsa(i);
  2 个评论
Brendan Hamm
Brendan Hamm 2015-6-25
I would like to reiterate you original statement. You say that you have a 20-by-1 vector positionsa.
Your error states:
??? Undefined function or method ' Positionsa ' for input arguments of type 'double'.
Error in ==> Untitled at 69 Alpha_posa=Positionsa(i);
Given this error, it is clear the command you typed is:
Alpha_posa=Positionsa(i); % Error!
MATLAB is case sensitive, so you need to type:
Alpha_posa = positionsa(i); % This should work if I is also defined
So the following set of commands will work:
positionsa = rand(20,1); % Random vector with 20 elements
i = 5; % An variable for indexing
Alpha_posa = positionsa(i) % Extract the 5th element.
marwa marwan
marwa marwan 2015-6-25
you are so right...samll error can confuse alot thank you for your time

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