I need the range of a vector. From the MATLAB documentation, it says "For vectors, range(x) is the range of the elements." However, whenever I try to use it, I get the error "Undefined function 'range' for input arguments of type 'double'." For example, if I use x=[1 2 3 4 5] and then do range(x), I will get this error. Am I crazy or is MATLAB screwing up here? I'm usually pretty good at figuring things out on my own but this one is stumping me.
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I have a struct as shown in picture, and I need to address one of the columns in a FOR loop, as shown. But I keep getting this error:
Function 'subsindex' is not defined for values of class 'struct'.
Error in analisa_arx_teste (line 351)
In my case, what i want is :line 1 represents i = 1, line 2 i =2; So, for features, When I ask for pref_estemod(i).features is to get the values from the field features associated to each model.
I am just starting programming with matlab, so all your help would be appreciated.
Thanks!
for i=pref_estemod(1:npreferred)
[m,n]=size(Training);
features=(pref_estemod(1,i).features);
end
The error lies in i=pref_estemod(1:npreferred).
If you intend to use i for indexing, the syntax is for i=1:npreferred.
1:npreferred itself expands to the horizontal array [1,2,...,npreferred]. = with a leading for is a special syntax combination. It means do the following code with i=1, i=2, ..., i=npreferred. Now I am sure you already know the idea behind for loop. The reason I write all this is to give you the following warning/advise. Do NOT expect the same syntax to work with non-numeric arrays. Because it works in some cases and not others.
I am using MATLAB R2015 and cannot implement 'butter' without getting an error related to too many output arguments from the polyfit part of the script. I have used the same implementation for years with other versions of MATLAB.
Example:
[b, a] = butter(2,[.15,.3]);
Error using poly
Too many output arguments.
Error in zp2ss (line 127)
den = real(poly(p(i:i+1)));
Error in butter (line 97)
[a,b,c,d] = zp2ss(z,p,k);
I get the same error implementing the examples in the help documentation.
Just a guess but is there any chance you've defined your own poly function? which('poly') should point to some Matlab directory unless you've defined it elsewhere, potentially as a variable?. For me on a newer version that path is something like $MATLAB/toolbox/matlab/polyfun/poly.m You can also edit the poly function edit poly and verify that there is one output argument for the function.
Also, I'd advise against ever writing decimal numbers without a leading zero. It took me way to long to figure out what [.15,.3] was. Instead write [0.15,0.3] or even just [0.15 0.3] Edit: I just realized that is an example in Matlab ... my point stands but the toolbox author should know better ...
Hi, I am trying to write a function as per the question. I have tried to create four sub-matrices which are the reverse of each other and then multiply to give the products demanded by the question. My attempt:
function T = custom_blocksT(n,m)
T(1:end,end-1:1);
T(1:end,end:-1:1)*2;
T(1:end,end:-1:1)*3;
T(1:end,end:-1:1)*4;
What I'm unsure of is
(i) What do the the indivual sub-matrices(T(1:end,end-1:1);)need to be equal to? I was thinking of(1:3)?
(ii) I tried to create a generic sub-matrix which can take any size matrix input using end was this correct or can't you do that? I keep getting this error
Undefined function or variable 'T'.
Error in custom_blocksT (line 2)
T(1:end,end-1:1);
I have searched the Matlab documentation and stacked overflow, but the problem is I'm not quite sure what I'm supposed to be looking for in terms of solving this question.
If someone could help me I would be very thankfull.
There are many problems with your function:
function T = custom_blocksT(n,m)
T(1:end,end-1:1);
T(1:end,end:-1:1)*2;
T(1:end,end:-1:1)*3;
T(1:end,end:-1:1)*4;
end
This is an extremely basic question, I highly recommend you find and work through some very basic MATLAB tutorials before continuing, even before reading this answer to be honest.
That said here is what you should have done and a bit of what you did wrong:
First, you are getting the error that T dos not exist because it doesn't. The only variables that exist in your function are those that you create in the function or those that are passed in as parameters. You should have passed in T as a parameter, but instead you passed in n and m which you don't use.
In the question, they call the function using the example:
custom_blocks([1:3;3:-1:1])
So you can see that they are only passing in one variable, your function takes two and that's already a problem. The one variable is the matrix, not it's dimensions. And the matrix they are passing in is [1:3;3:-1:1] which if you type in the command line you will see gives you
[1 2 3
3 2 1]
So for your first line to take in one argument which is that matrix it should rather read
function TOut = custom_blocks(TIn)
Now what they are asking you to do is create a matrix, TOut, which is just different multiples of TIn concatenated.
What you've done with say TIn(1:end,end-1:1)*2; is just ask MATLAB to multiple TIn by 2 (that's the only correct bit) but then do nothing with it. Furthermore, indexing the rows by 1:end will do what you want (i.e. request all the rows) but in MATLAB you can actually just use : for that. Indexing the columns by end-1:1 will also call all the columns, but in reverse order. So in effect you are flipping your matrix left-to-right which I'm sure is not what you wanted. So you could have just written TIn(:,:) but since that's just requesting the entire matrix unchanged you could actually just write TIn.
So now to multiply and concatenate (i.e. stick together) you do this
TOut = [TIn, TIn*2; TIn*3, TIn*4]
The [] is like a concatenate operation where , is for horizontal and ; is for vertical concatenation.
Putting it all together:
function TOut = custom_blocks(TIn)
TOut = [TIn, TIn*2; TIn*3, TIn*4];
end
I'm trying to write a bit of code of to make MATLAB scatter plots from variables in a structure. I want to give the code the name of the structure (there will be many of these structures) and then get it to make a scatter plot of two variables. When I try the code below I get an error message saying, "??? Error: File: make_graphs.m Line: 6 Column: 9
The input character is not valid in MATLAB statements or expressions."
str2stuct= input('Please enter the string for the struct e.g. TMB_RUN_1_data:');
test1=strcat(str2stuct,'.NDROP_max');
test2=strcat(str2stuct,'.input_kappa');
scatter($(test2), $(test1))
I thought that the error message probably meant that I was using the dollar sign in a way which MATLAB doesn't approve of (I've yet to find much use for $ in MATLAB).
I tried it like this:
str2stuct= input('Please enter the string for the struct e.g. TMB_RUN_1_data:');
test1=strcat(str2stuct,'.NDROP_max');
test2=strcat(str2stuct,'.input_kappa');
scatter((test2),(test1))
And got this error:
"??? Error using ==> scatter at 51
Must supply X and Y data as first arguments.
Error in ==> make_graphs at 6
scatter((test2),(test1)) "
I tried it with changing the last line as shown below but got the same error as with the brackets:
scatter(test2,test1)
If I use the literal name as below it works fine.
scatter(TMB_RUN_1_data.NDROP_max,TMB_RUN_1_data.input_kappa)
I've tried a bunch of other things but I am not getting it. I've tried the mathworks pages on scatter but there are no examples that are close to what I am doing. I am really really stuck.
EDIT: I have found a solution but I am aware that this is not considered best practice. If you can simply explain how to do this better that would be good. Answers should be aimed at a moron in a hurry, not an experienced programmer.
Making this the last line works:
scatter(eval(test2),eval(test1))
I am aware that 'eval' is frowned upon and so this probably isn't a good long term answer, works for now. This seems to be the way to get MATLAB to actually read the contents of the strings test1 and test2 into the lines in question.
What does the code
error(abcdchk(a,b,c,d));
in MATLAB do? I'm trying to run a MATLAB script with this code snippet in Octave and getting
error: 'abcdchk' undefined near line 57 column 7
error: evaluating argument list element number 1
How can I fix this?
There appear to be multiple versions of the abcdchk() function out there (kind of depends on where you got the code from), for example this one from caltech and this one from Georgia Tech, but they all seem to check that the dimensions of the given matrices are consistent.