// I made function like this:
function y = ZL(L,f)
if isvector(f)
y=1j*2*pi.*f*L;
else
y=1j*2*pi.*f*L;
end
// and command :
L = 10,
f= -10000:100:10000,
ZL=ZL(L,f);
// then error :
index should be positive integer(not complex format integer) or boolean
-> this error is translated by me who is Korean; sorry
what's wrong with it?
First time you call ZL = ZL(L,f), you don't get any error.
If you try to call your command a second time, you'll get this error: Index exceeds matrix dimensions. It's because you affect the variable ZL, so the second time it's not the function you're calling but you"re trying to get elements from the array ZL.
So please don't use same name for a variable and an existing function, otherwise the function name is masked by the variable.
Related
Having this long task that I will resume:
Perform a regression model over the normalized active cases in China using the model.....(long assignment that I'm not worried about and will save you time). Tip: To convert from datetime to a numeric variable for the regression, use x=day(date-min(date(:)))+1; being “date” the datetime vector return from getdata function.
This is what I have:
function RP_ejercicio1
data = readtable('COVID-19.csv');
[active_res, confirmed_res, death_res, recovered_res, date] = getdata(data, 'China', 93/147);
x=day(date-min(date(:)))+1;
y = active_res;
yp = log(y./x);
a = [x ones(size(x))];
sol = inv(a'*a)*(a'*yp);
b = sol(1);
c = sol(2);
a = exp(c);
end
I get this error: Check for missing argument or incorrect argument data type in call to function 'day'. In this line: x=day(date-min(date(:)))+1;. The one that is supposed to help as a tip is giving me a headache. I can ensure that date is a 1x50 datetime array after executing the getdata function.
Am I doing something wrong? Is the tip wrong? And if it's the second case, is there other way to do the same?
I add an image for more clarity:
Date array
As somebody said here, you should be using the function days.
I wrote a function, wins_plot, to read the scoreboard from a file and store the player's name, number of plays, wins, & losses. I stored all those using struct. I loop over the file, store each line in line, textscan for everything I need from line, and then iterate i (initially == 1) as I go to expand my array of structures. A snippet from the code to represent what I am saying:
c = textscan(line, '%s %s %d %d %d');
player(i).firstName = c{1};
player(i).lastName = c{2};
player(i).plays = c{3};
player(i).wins = c{4};
player(i).losses = c{5};
After all the file has been scanned and stored, I then write this code to extract the number of wins of each player and store it in X and then finally use the pie function to represent the values in X
for n=1:(i-1)
X(n) = player(n).wins;
end
pie(X);
I get a wall of error after:
Undefined function 'cos' for input arguments of type 'int32'.
Error in pol2cart (line 22) x = r.*cos(th);
Error in pie (line 99)
[xtext,ytext] = pol2cart(theta0 + x(i)*pi,1.2);
Error in wins_plot (line 30) pie(X);
I have no clue what might be wrong. Any help would be greatly appreciated. Please keep in mind that I only just started learning MATLAB today so my knowledge of it is very limited (and I have R2013a). Thank you in advance!
The numbers got read as int32, but when you call pie, it requires them to be double to do the computation. So, when you call pie, try casting the values to double. Try this,
pie(double(X));
I want to find the Minimum of a function using
[x,fval] = fminsearch(#(param) esm6(param,identi),result(k,1:end-1),options)
now for each Iteration step i want some values that the function 'esm6' calculates to be saved in an Array. I tried the following:
In the first line of the function i wrote
identi.sim.i_optiIter = identi.sim.i_optiIter + 1;
to have an iteration-variable counting the iteration steps of fminsearch. And later to catch the values that I need I used
identi.sim.guete_werte.gew(identi.sim.i_optiIter,:,:) = y_sim;
identi.sim.guete_werte.ungew(identi.sim.i_optiIter,:,:) = y_sim_ungew;
and to make sure that I use the new values of the identi-struct for the next function call, I wrote this at the end of the function:
assignin('base','identi',identi);
Now unfortunatly it doesn't do what I wanted it to do. Can anyone help me with this?
EDIT:
I made another attempt on it, using an Output function. I extendend my Options like this:
options = optimset('Display','iter','MaxIter',3,'OutputFcn',#outfun);
But now the Problem is that i cannot figure out where to put this outfun. The outfun Looks like this:
function stop = outfun(x,optimvalues,state,iteration,y_sim,y_sim_ungew)
stop = false;
if state == 'iter'
guete_werte.gew(iteration,:,:) = y_sim;
guete_werte.ungew(iteration,:,:) = y_sim_ungew;
end
end
Now the Problem with it is, that i can not put it in the file, where i call the fminsearch, because that is a script. If i put the outputfunction into a separate .m-function file, it is not able to Access the variables of the esm6 function. And if I add it to the esm6-function file, matlab can't find the function and says
??? Error using ==> feval Undefined function or method 'outfun' for
input arguments of type 'struct'.
I've got such a problem using MATLAB:
I wrote this function:
function E = f(x, lamda)
E = 1 - exp(-lamda * x);
end
When I write: Prob = f(1000, lamda); where lamda = 3.4274e-004
I get this error:
??? Attempted to access f(1000,0.000341565); index must be a positive integer or logical.
I understand that it requires a positive integer, but why ? I need lamda to be real. What's the problem here ? Can you, please, tell me where I'm wrong?
You have a function f and a variable f declared at the same time. Do clear f; then try your code again. What's happening here is that the variable declaration takes precedence over your function and so doing f would try and access the variable f first.
If you're using f as a variable somewhere and can't change this, then rename your function to be something other than f... perhaps... comp or something. Once you do this, make sure you change your file name so that it's called comp.m, then do:
Prob = comp(1000, lamda);
Your error message indicates that there is a variable called f in your workspace and matlab thinks you are trying to access its elements. Remove the variable f with clear('f') or rename the function to something else and you should be fine.
I have been using MATLAB fminunc function to solve my optimization problem. I want to try the minFunc package :
http://www.di.ens.fr/~mschmidt/Software/minFunc.html
When using fminunc, I defined a function funObj.m which gives me the objective value and the gradient at any point 'x'. It also takes in several external inputs say, {a,b,c} which are matrices. So the function prototype looks like :
function [objVal,G] = funObj(x,a,b,c)
I want to use the same setup in the minFunc package. From the examples, I figured this should work :
options.Method='lbfgs';
f = #(x)funObj(x,a,b,c);
x = minFunc(f,x_init,options);
But when I call this way, I get an error as:
Error using funObj
Too many output arguments.
What is the correct way to call minFunc for my case?
**EDIT : Alright, here is a sample function that I want to use with minFunc. Lets say I want to find the minimum of a*(b-x)^2, where a,b are scalar parameters and x being a scalar too. The MATLAB objective function will then look like :
function obj = testFunc(x,a,b)
obj = a*(b-x)^2;
The function call to minimize this using fminunc (in MATLAB ) is simply:
f = #(x)testFunc(x,a,b);
x = fminunc(f,x_init);
This gives me the minimum of x = 10. Now, How do I do the same using minFunc ?
"Note that by default minFunc assumes that the gradient is supplied, unless the 'numDiff' option is set to 1 (for forward-differencing) or 2 (for central-differencing)."
The error is because only one argument is returned by the function. You can either return the gradient as a second argument or turn on numerical differencing.
Agree with Mark. I think the simplest way to solve it is
minFunc(#testFunc, x_init, a, b, c)
In MATLAB temporary function can only have one return value. So f = #(x)testFunc(x,a,b); let your method drop gradient part every time. Because minFunc can accept extra paramters, you can pass a, b and c after x_init. I think this would work.