I have a problem at the beginning of my function. The function is to combine several data column from some objects. Error happens at the beginning of function. It says as follows:
Error in find_by_coor (line 2)
for i = 1:length(obj_ac)
Here is only the declaration of variable and loop, but Matlab somehow returned error. I have no idea so would like someone to help me. I attached my code as follows. Thanks a lot in advance.
function arr = find_by_coor(obj_ac,obj_gps,obj_sen_dir,lat1,long1,lat2,long2)
for i = 1:length(obj_ac)
if eq(obj_sen_dir(i).sensor,4) && strcmp(obj_sen_dir(i).direction,'outbound')
ind = obj_gps(i).save_var_gps(:,1)>lat1;
if isempty(find(ind)) == 1
continue
end
temp = obj_gps(i).save_var_gps(ind,:);
ind = temp(:,1)<lat2;
if isempty(find(ind)) == 1
continue
end
temp2 = temp(ind,:);
ind = temp2(:,2)<long1;
if isempty(find(ind)) == 1
continue
end
temp3 = temp2(ind,:);
ind = temp3(:,2)>long2;
if isempty(find(ind)) == 1
continue
end
temp4 = temp3(ind,:);
mint = min(temp4(:,5))-min(obj_gps(i).save_var_gps(:,5));
maxt = max(temp4(:,5))-min(obj_gps(i).save_var_gps(:,5));
if isempty(mint) == 1 || isempty(maxt) == 1
continue
end
if floor(mint*(1.6516e+03)) == 0 || floor(maxt*(1.6516e+03)) == 0
continue
end
temp5 = obj_ac(i).save_var(floor(mint*(1.6516e+03)):floor(maxt*(1.6516e+03)));
temp6 = abs(fft(temp5));
arr(i,:) = [i objs(i).daten var(temp5) max(temp5) min(temp5) mean(temp5) std(temp5) mode(temp5) var(temp6) max(temp6) min(temp6) mean(temp6) std(temp6) mode(temp6)];
disp(i);
end
end
end
The problem is that when you run the function, the output variable arr is never assigned. In Matlab you must always assign a function output if you choose to have it in the definition. For example
function [a,b] = setAB()
err = 0; % Gives an error if err is true
a = 1;
if ~err
b = 1;
end
The reason is most certainly that for some inputs, all values fall into one of the if statements and you do never reach the point where arr is assigned. A good solution for this is to assign a default value for arr in the beginning. That may for example be nan or -1 or, in your case maybe an array arr = nan(wanted size) or arr = -1*ones(wanted size). If you do not preallocate arr you will likely get a "matrix out of bounds" error instead, should you solve the first issue.
It does not mean that you always need to have an output though.
function [] = noOutput()
disp('Hi, I am a void!');
You may also choose to return as many values as number of outputs.
function varargout = variableArgs()
a = 1;
b = 2;
c = 3;
if (nargout == 1)
varargout{1} = a;
elseif (nargout == 2)
varargout{1} = b;
varargout{2} = c;
else
error('Wrong number of output arguments!');
end
I am not saying which of the approaches you should use or that any of them are good. Normally I use varargout in case I write plotting functions. Then I may want to return nothing in case I do not have an output argument. Then I want to return handles or any extra information. Further as you may have understood there is also a varargin that may be of more use.
Related
I made a simple function that loops between the rows and columns of an array using for loops. The loop is part of a function named checktakentest (Since I'm testing this method atm). I keep getting the error that there aren't enough input arguments.
function [spotTaken] = checktakentest(tttArray)
for h = 1:3
if tttArray(h,j) == 1
%Is spot is taken, break loop
spotTaken = 1; break;
else
spotTaken = 0;
end
for j=1:3
if tttArray(h,j) == 1
spotTaken = 1; break;
else
spotTaken = 0;
end
end
end
I tried also defining h and j previously as follows
h = [1,2,3];
j = [1,2,3];
Note that tttArray is a global variable defined in another function and its array values change in that function. A spot taken is 1, empty is 0. What arguments should I pass to the function and how do I know which ones to pass since this has been a recurring problem for me? A simple explanation would be appreciated. Note that I call the function via
checktakentest(tttArray)
Just remove the first if clause - at that point you don't have j initialized to a value, so you can't use it, yet:
function [spotTaken] = checktakentest(tttArray)
for h = 1:3
for j=1:3
if tttArray(h,j) == 1
spotTaken = 1; break;
else
spotTaken = 0;
end
end
end
If you call your function like this: checktakentest(tttArray) with tttArray beeing a mxn-matrix with m>2 and n>2 you should not get an error.
If you call it like this: checktakentest you will get the error you described (not enough input arguments).
In a matrix, how does one set an adjacent and diagonal element to 1 if the values in these locations are the same avoiding a for loop?
An attempt made with for loop is given
[r,c] = size(mat1);
Sval = zeros(size(mat1));
for i = 1:r
for j = 1:c-1
if(mat1(i,j) == mat1(i,j+1))
Sval(i,j) = 1;
Sval(i,j+1) = 1;
else
Sval(i,j) = 0;
Sval(i,j+1) = 0;
end;
end;
end;
To receive the exact same output without the loops the code is the following. However it is not quite clear what you want to achieve with this code. Please elaborate further if this doesn't answer your question.
Sval = mat1(:,1:c-1) == mat1(:,2:c);
Sval(:,c) = Sval(:,c-1);
If I interpret your sentence right what you actually want is to shift/copy the equal values to the right as well. This could be achived by:
Sval = mat1(:,1:c-1) == mat1(:,2:c);
Sval(:,c) = zeros(r,1);
Sval(:,2:c) = Sval(:,1:c-1) | Sval(:,2:c);
I have a function usenum
function TF = usenum(x)
TF = false;
if ~isnumeric(x)
h = msgbox('Input is not numeric');
elseif (x <= 0)
h = msgbox('Input must be > 0');
else
TF = true;
end
I am getting user input in the main menu:
answer = inputdlg(prompt,dlg_title,num_lines,def);
The inputdlg has 2 values and can be indexed by {1} and {2}
I want to wait for the user to input a value, the value has to be a number and greater than 0. in the case that he doesn't, I want to output the respective message and make him keep inputting until he gets it right, or close the inputdlg dialog.
I am attempting something like this:
condition = false;
while ~condition
answer = inputdlg(prompt,dlg_title,num_lines,def);
numOfTracks = answer{1};
bpmRange = answer{2};
condition = usenum(numOfTracks);
end
I am trying to say, while condition = false, i.e. while input is not numeric or not greater than 0, keep getting user input. Once the user inputs a valid number the condition is supposed to become true and the while is supposed to terminate. However, the inputdlg keeps opening for input and the only way I can stop it is by closing it (infinite loop). how can I achieve what I want?
Thanks in advance
Your loop appears to be correct. The following testing provides results of your usenum function.
>> usenum('')
ans =
0
>> usenum(-1)
ans =
0
>> usenum(1)
ans =
1
Your usenum function is correct as far as typing is concerned, but I believe your input is always given as a string since you're getting user input from a dialogue. Instead, you should try redefine usenum as follows if you're expecting a string input. The function str2double converts it to a double and if it's text, it will show as NaN. That's what the isnan check is for, to check if it's text.
function TF = usenum(x)
% Default to false
TF = false;
x = str2double(x);
% Check if digits
if isnan( x )
h = msgbox('Input is not numeric');
elseif (x <= 0)
h = msgbox('Input must be > 0');
else
TF = true;
end
This is the result of the new function.
>> usenum('a')
ans =
0
>> usenum('-1')
ans =
0
>> usenum('1')
ans =
1
I'm trying to code a function calculating difference quotients. I need to this for polynomial interpolation. Given nodes x = linspace(a,b,n+1), function values at the nodes y = func(x) I want to find the values of difference quotients f[x0], f[x_0,x_1], ..., f[x_0,x_1,...,x_n]. To calculate f[x_0,x_1,...,x_n] I will need f[x_0,x_1,...,x_(n-1)], etc., thus it would be a good idea save the intermediate steps on my way to f[x_0,x_1,...,x_n], so that on my way to f[x_0,x_1,...,x_n] I will save the preceding difference quotients as elements of a vector.
Could someone tell me how to correct my code in order to save appropriate difference quotient values? Here's the code:
function [fx, all_fx] = ilo2(a,b,x,y,fx,all_fx)
if a == b
fx(end+1) = y(a);
if a == 1
all_fx(end+1) = fx(end);
end
return
end
a;
b;
[c, all_fx] = ilo2(a+1,b,x,y,fx,all_fx);
[d, all_fx] = ilo2(a,b-1,x,y,fx,all_fx);
fx(end+1) = (c-d)/(b-a);
if a == 1
all_fx(end+1) = fx(end);
end
end
The difference quotients I need are under 'if a == 1' condition.
Ok, I think I fixed it:
function [all_fx,fx] = ilo(a,b,x,y,all_fx,fx)
if a == b
fx(end+1) = y(a);
if a == 1
all_fx(end+1) = fx(end);
end
return
end
[all_fx,c] = ilo(a+1,b,x,y,all_fx,fx);
[all_fx,d] = ilo(a,b-1,x,y,all_fx,fx);
fx(end+1) = (c-d)/(b-a);
if a == 1
all_fx(end+1) = fx(end);
end
end
Hi all I am working on checking for certain cases in a large loop, with in this large loop is this statement:
%Center Dialouge
timers_c = [start_dpc_sh_hi_timer_c, start_dpc_sh_lo_timer_c, start_ffm_sh_act_hi_timer_c,...
start_ffm_sh_act_lo_timer_c, start_hpot_eff_loss_timer_c, start_lfpt_dpsh_timer_c,...
start_pc_sh_time_c, start_post_tl_nl_c, start_pre_tl_nl_c, start_elec_lu_timer_c];
if perf_case_c ~= -1
for k = 1:10
if iscellstr(timers_c(k)) == 1
perf_case_timer_c = timers_c{k};
timer_set_c = 1;
end
end
end
To I identify the start time and the case type to be output in a dialogue message:
if timer_set_c == 1
pcase_c = msgbox([sprintf('%s'),perf_case_c,sprintf('\nMET:%s\n'),perf_case_timer_c],'PERFORMANCE CASE');
end
I can't get the if statement that determines which case has been determined to work. I am trying to use the change from -1 to a string somehow, but it doesn't quite work.
A minimal example would be
%Assume all timers initialized as zero
%Assume case ~= -1 (is a char array, string
timers_c = [timer1, timer2, timer3 ]
if case ~= -1
for k = 1:3
if iscellstr(timer_c(k)) ==1
case_time = timers(c{k});
time_set_flag = 1
end
end
end
...
and then outside of the loop would be the above msgbox