I'm using some user generated functions in MatLab. It'll be quicker if I don't post my actual code here so I'll summarize.
I have two functions. Each of them exist in their own files saved under their proper names. They can be called and work correctly. Lets say function1 is:
function [Output1] function1=(a,b)
Output1=a+b
end
function [Output2] function2=(a,Output1)
Output2=a+Output1
end
new script file
a=2;
b=3;
function1(a,b);
function2(a,Output1);
This doesn't work, because function1 isn't posting Output1 into the workspace. How do I make it do that?
Check this tutorial. This is how you are supposed to write a function.
function Output1 = function1(a, b)
Output1 = a + b;
end
Then your second function will get the input like this.
function Output2 = function2(a, Output1)
Output2 = a + Output1;
end
Of course you need to store answers of functions into variables to have them stored in the workspace.
aa=2;
bb=3;
Output11 = function1(aa,bb);
Output22 = function2(aa,Output11);
If you don't use Output11 and Output22, functions will store their result into ans variable in the workspace. And obviously, apart from the fact that you cannot pass the variable to the second function as Output1, second function will overwrite the ans.
Related
I have code which is in multiple function files, input to these functions are stored in one file called inputfile.m(script file), in which I assigned some constant values to the inputs. These values act as a input to several function files named degree_eq.m(function file).
How I can write the code so that every time of execution, function files takes the required inputs from the inputfile.m.
Let's say you have two functions, one with your inputs (inputfile) and one where you do stuff (do_stuff).
function [a,b,c] = inputfile()
%define your constants
a=10;
b=100;
c=8.3;
function z = do_stuff()
[a, b, c] = inputfile() %takes the inputs from inputfile.m
z = a*c - b;
You can exploit the fact that matlab variables are persistent outside their scope. Lets say you have 6 constants a,b,c,d,e,f defined in input file. So what can be done is, write a top script called top.m which would be something like
inputfile
degree_eq1(a,b,c)
degree_eq2(c,d,e)
A third approach (combining Nirvedh Meshram and qbzenker answers) is to call an input script inside your MATLAB functions.
The advantage is that you do not have to specify which parameters are needed from or specified in your input script, but this is a disadvantage too, because the needed inputs are not made explicit. So, it is much more error prone. I only recommend this approach for a large number of input variables.
inputfile.m:
a = 5;
b = 8;
c = 10;
degree_eq.m:
function d = degree_eq()
inputfile;
d = a + b + c;
end
As an alternative, you can specify which input file to use:
degree_eq.m:
function d = degree_eq(inputFilename)
eval(inputFilename);
d = a + b + c;
end
and call it as follows:
degree_eq('inputfile');
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'.
Suppose the matrix is A which is in a m file new1.m . Now I want to access this matrix to another m file new2.m . How can it be done ?
Your question is a little nonspecific, but I'll try to answer.
There are several ways to do this,
Assuming that you have a m-file (script) named 'new1' with (for example) A = rand(4) in it. You could just run it in new2.m before you want to use A
new1;
B = 2*A;
Note that new1 will return all the other variables assigned in it, flooding your workspace. Perhaps not a problem, but if so, you could just clear them with
clear var1 var2 var2 etc.
Another way is to make new1 into a function and return (only) A
function A = new1()
but I'm guessing that might ruin some other purposes of new1.
In that case you could return A only if the function is called with a special input argument (for example 'getA')
function new1(varargin)
...
... % some code
...
if nargin && strcmp(varargin{1},'getA')
assignin('caller','A',A);
end
And so from new2, just call the function.
new1('getA');
I am creating a function with two inputs, and would like to know how I can name the output accorinding to the name of the inputs.
E.g.
function [padded_*input_name*] = padstruct(S, F)
later in code...
else
padded_*input_name* = padarray(toPad, (longest - size(toPad,1)), NaN('double'), 'post');
So if I enter a struct (labelled as S in the input arguments) called my_struct, I would like to get an output called padded_my_struct. But this should be free to change according to the name of the input struct. I want to do this because I have a lot of structs to run through this function and I want to explicitly know from the output name, which is which.
I am a beginner with Matlab and so would appreciate any exaplanation or references to literature.
I don't quite give you what you want. Instead, I have a function that, given the inputs Account and F, produces in the base workspace a variable "padded_Account", and returns the name of the variable it creates.
function padded_Sname_str=padstruct(Sin,F)
%get the name of the structure used in the function call here
Sname=inputname(1);
%do stuff to Sin here
Sin.pad=F; %this is just my test operation
%create the name of the new variable you want
padded_Sname_str=['padded_',Sname];
%this creates it in the base workspace, since passing back as an
%output argument doesn't preserve the name
assignin('base',padded_Sname_str,Sin)
return
Hope this is helpful. Cheers!
Try this -
function [padded_*input_name*] = padstruct(S, F)
%// .. later on in code
else
value = padarray(toPad, (longest - size(toPad,1)), NaN('double'), 'post');
evalc(['padded_' inputname(1) '= value']);
Let us know if it works for you!
I'm pretty new to MATLAB and I have a simple question. What if I have the following structured functions:
function[A] = test(A)
test1(A);
test2(A);
end
function test1(A)
#% do something with A
end
function test2(A)
#% do something else with the newly modified A
end
How do I pass around A from function to function keeping it's modified nature? (Suppose A is a matrix)
EDIT: let's make the situation a little simpler. Suppose my main function is:
function[a]=test(a)
test1(a);
#%test2(a);
end
and test1() is defined as:
function[a] = test1(a)
a=5;
end
Then, I call the function test with test(3), and I want it to report ans = 5, yet it still reports ans = 3.
Thanks!
Variables in MATLAB are passed using "call by value" (with some exceptions), so any value that you pass to a function and modify has to be returned from the function and either placed in a new variable or the old variable overwritten. Returning the value of a variable from a function is simple: you just place the variable name in the output argument list for the function.
For your example, you would do this:
function A = test(A)
A = test1(A); %# Overwrite A with value returned from test1
A = test2(A); %# Overwrite A with value returned from test2
end
function A = test1(A) %# Pass in A and return a modified A
#% Modify A
end
function A = test2(A) %# Pass in A and return a modified A
#% Modify A
end
One thing to be aware of is variable scope. Every function has its own workspace to store its own local variables, so there are actually 3 unique A variables in the above example: one in the workspace of test, one in the workspace of test1, and one in the workspace of test2. Just because they are named the same doesn't mean they all share the same value.
For example, when you call test1 from test, the value stored in the variable A in test is copied to the variable A in test1. When test1 modifies its local copy of A, the value of A in test is unchanged. To update the value of A in test, the return value from test1 has to be copied to it.
Return the object from the function and then pass it on to the next function.