undefined variable error message
in [Matlab]
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From: Nathan on 22 Mar 2010 20:46 On Mar 22, 5:38 pm, "J Bell" <superblind...(a)gmail.com> wrote: > "Oleg Komarov" <oleg.komarovRemove.t...(a)hotmail.it> wrote in message <ho922l$t3...(a)fred.mathworks.com>... > > > when I run it, I get the message > > > > ??? Input argument "Y" is undefined. > > > > Error in ==> dumb at 3 > > > err=Y-X*beta; > > > > any help? > > > > thanks > > > > why does this error message appear in general? > > > Be more precise, how do you run it? > > > It appears whenewer you try to use a variable that doesn't exist yet in the workspace. > > > An example: > > clear > > a = 1+c; > > > Oleg > > I saved an m file with the name "dumb.m" containing this code, and in Matlab navigated to the location of this m file so that it appears in the "Current Directory" window. I run it by typing "dumb" and pressing enter in the command window. Perhaps this is the problem? That is the problem. What value would you expect to be in Y, X, or beta, if you don't tell the program what values they are supposed to be? If that is the extent of your function, try typing this in the matlab command window: %arbitrary data values: Y = 5; beta = .01; X = 4; %function call dumb(beta,Y,X) -Nathan
From: J Bell on 22 Mar 2010 21:13 Nathan <ngreco32(a)gmail.com> wrote in message <cd8c0f96-ec6b-47bc-8c0c-2d8b4dd441cb(a)d30g2000prn.googlegroups.com>... > On Mar 22, 5:38 pm, "J Bell" <superblind...(a)gmail.com> wrote: > > "Oleg Komarov" <oleg.komarovRemove.t...(a)hotmail.it> wrote in message <ho922l$t3...(a)fred.mathworks.com>... > > > > when I run it, I get the message > > > > > > ??? Input argument "Y" is undefined. > > > > > > Error in ==> dumb at 3 > > > > err=Y-X*beta; > > > > > > any help? > > > > > > thanks > > > > > > why does this error message appear in general? > > > > > Be more precise, how do you run it? > > > > > It appears whenewer you try to use a variable that doesn't exist yet in the workspace. > > > > > An example: > > > clear > > > a = 1+c; > > > > > Oleg > > > > I saved an m file with the name "dumb.m" containing this code, and in Matlab navigated to the location of this m file so that it appears in the "Current Directory" window. I run it by typing "dumb" and pressing enter in the command window. Perhaps this is the problem? > > That is the problem. > > What value would you expect to be in Y, X, or beta, if you don't tell > the program what values they are supposed to be? > > If that is the extent of your function, try typing this in the matlab > command window: > %arbitrary data values: > Y = 5; > beta = .01; > X = 4; > %function call > dumb(beta,Y,X) > > > -Nathan I made this very cumbersome by not including the other code, that which defines the variables, sorry, here it is: beta=[1;0]; X=[ones(N,1) rand(N,1)]; mu=randn(N,1); Y=X*beta+mu; So Y is defined here. I should have included this before, sorry. So the variable "Y" appears in the workspace with the value listed as "<500x1 double>" After running this in the command window, I still get the error message.
From: Matt Fig on 22 Mar 2010 21:28 Type this, then hit return: >>docsearch('function syntax') then read it all.
From: Walter Roberson on 22 Mar 2010 21:33 J Bell wrote: > I made this very cumbersome by not including the other code, that which > defines the variables, sorry, here it is: > > beta=[1;0]; > X=[ones(N,1) rand(N,1)]; > mu=randn(N,1); > Y=X*beta+mu; > > So Y is defined here. I should have included this before, sorry. > So the variable "Y" appears in the workspace with the value listed as > "<500x1 double>" Yup, but that's in the "base workspace" that it is defined, not in the workspace of your function. A variable name in your function need not have a single thing to do with a similar variable name in the base workspace or in the calling function. The content of the 'Y' variable in your function is determined entirely by the _value_ of what you pass to the function in the corresponding argument *position*. Just do like an earlier poster suggested, and invoke the function from the command window, e.g., dumb(beta,Y,X) That would take the _value_ of beta from the current workspace and make it available to the function 'dumb' under whatever name you listed first in the arguments in the 'function' statement.
From: Sadik on 22 Mar 2010 21:34
Hi, The problem could well be that you have more than one dumb.m's... Please type the following in the command window: which -all dumb This is going to give you the list of all different dumb.m's under different folders. One solution to your problem could be to go directly to the folder in which your three-input dumb.m resides [the one with syntax dumb(beta,Y,X)]. And the bottom line is that we should never write two or more functions with the same name. :-) [Of course, if that is the case...] Best. |