I am using JES and am wondering what built in function I should use to make this effect work.
newG=(oldG+(abs(x*y*2.57901)%64))%256
So far I have this code
def forLoop():
picture = makeEmptyPicture(300,200)
show(picture)
for p in getPixels(picture):
setColor(p,black)
repaint(picture)
for p in getPixels(picture):
oldG=(p)
newG=(oldG+(abs(x*y*2.57901)%64))%256
repaint(picture)
The error I get is
The error was:x Name not found globally.
A local or global name could not be found. You need to define the function or variable before you try to use it in any way.
you'll need to define the local names for x and y to be able to get the newG color, hope this helps
coding is something like this:
x= getX(p)
y= getY(p)
Related
I've tried to do it like this:
I've found this https://www.quora.com/How-do-I-draw-a-parabola-in-MATLAB and tried to use it like that:
a=str2double(get(handles.InputA,'string'));
b=str2double(get(handles.InputB,'string'));
c=str2double(get(handles.InputC,'string'));
xLine=[(-b)/2*a-5:0.01:(-b)/2*a+5];
yToPlot= a*x.^2 + b.x+c;
plot(xLine,yToPlot);
but I keep getting errors...any help would be appreciated
You define the variable xLine, but use the variable x in yToPlot. That's why you get an error saying x is not defined. Also in yToPlot you have b.x. MATLAB then thinks that b is a struct and that you want to access the field named x of b. Since b is not a struct, and doesn't have a field x, you'll get the error 'Attempt to reference field of non-structure array.'. If you fix these two, it should work, according to the code you've given:
xLine=[(-b)/2*a-5:0.01:(-b)/2*a+5];
yToPlot= a*xLine.^2 + b*xLine+c;
plot(xLine,yToPlot);
GAMS: I think I have a pretty simple question, however I'm stuck and was wondering if someone could help here.
A simplified version of my model looks like this:
set(i,t) ;
parameter price
D;
variable p(i,t)
e(i,t);
equations
Equation1
obj.. C=sum((i,t), p(i,t)*price);
Model file /all/ ;
Solve file minimizing C using MIP ;
Display C.l;
p(i,t) and e(i,t) are related:
Equation1 .. e(i,t)=e=e(i,t-1)+p(i,t)*D
Now I want to retrieve information from the solution: lets say I want to know at what t e(i,t) has a certain value for example --> e(i,t)= x(i) or otherwise formulated e(i,t=TD)=x(i) find TD, where x(i) thus is depending on i. Does anyone know how I can write this in to my GAMs model? To be clear I do not want to change anything about my solution and the model I have runs; I just want to retrieve this information from the solution given.
So far I tried a couple of thing and nothing worked. I think that this must be simple, can anyone help? Thank you!
Try something like this:
set i /i1*i10/
t /t1*t10/;
variable e(i,t);
*some random dummy "solution"
e.l(i,t) = uniformInt(1,10);
set find5(i,t) 'find all combinations of i and t for which e.l=5';
find5(i,t)$(e.l(i,t)=5) = yes;
display e.l,find5;
Hope that helps,
Lutz
I've been looking throught the documentation, but can't seem to find the bit I want.
I have a for loop and I would like to be able to view every value in the for loop.
for example here is a part of my code:
for d = 1 : nb
%for loop performs blade by blade averaging and produces a column vector
for cc = navg : length(atbmat);
atb2 = (sum(atbmat((cc-(navg-1):cc),d)))/navg;
atbvec2(:,cc) = atb2;
end
%assigns column vector 'atbvec2' to the correct column of the matrix 'atbmat2'
atbmat2(d,1:length(atbvec2)) = atbvec2;
end
I would like to view every value of atb2. I'm a python user(new to MATLAB) and would normally use a simple print statement to find this.
I'm sure there is a way to do it, but I can't quite find how.
Thankyou in advance.
you can use disp in Matlab to print to the screen but you might want to use sprintf first to format it nicely. However for debugging you're better off using a break point and then inspect the variable in the workspace browser graphically. To me, this is one of Matlab's best features.
Have a look at the "Examine Values" section of this article
The simplest way to view it everywhere is to change this line:
atb2 = (sum(atbmat((cc-(navg-1):cc),d)))/navg;
Into this, without semicolon:
atb2 = (sum(atbmat((cc-(navg-1):cc),d)))/navg
That being said, given the nature of your calculation, you could get the information you need as well by simply storing every value of abt2 and observing them afterwards. This may be done in atbmat2 already?
If you want to look at each value at the time it happens, consider setting a breakpoint or conditional breakpoint after the line where abt2 is assigned.
I want to create a structure with a variable name in a matlab script. The idea is to extract a part of an input string filled by the user and to create a structure with this name. For example:
CompleteCaseName = input('s');
USER WRITES '2013-06-12_test001_blabla';
CompleteCaseName = '2013-06-12_test001_blabla'
casename(12:18) = struct('x','y','z');
In this example, casename(12:18) gives me the result test001.
I would like to do this to allow me to compare easily two cases by importing the results of each case successively. So I could write, for instance :
plot(test001.x,test001.y,test002.x,test002.y);
The problem is that the line casename(12:18) = struct('x','y','z'); is invalid for Matlab because it makes me change a string to a struct. All the examples I find with struct are based on a definition like
S = struct('x','y','z');
And I can't find a way to make a dynamical name for S based on a string.
I hope someone understood what I write :) I checked on the FAQ and with Google but I wasn't able to find the same problem.
Use a structure with a dynamic field name.
For example,
mydata.(casename(12:18)) = struct;
will give you a struct mydata with a field test001.
You can then later add your x, y, z fields to this.
You can use the fields later either by mydata.test001.x, or by mydata.(casename(12:18)).x.
If at all possible, try to stay away from using eval, as another answer suggests. It makes things very difficult to debug, and the example given there, which directly evals user input:
eval('%s = struct(''x'',''y'',''z'');',casename(12:18));
is even a security risk - what happens if the user types in a string where the selected characters are system(''rm -r /''); a? Something bad, that's what.
As I already commented, the best case scenario is when all your x and y vectors have same length. In this case you can store all data from the different files into 2 matrices and call plot(x,y) to plot each column as a series.
Alternatively, you can use a cell array such that:
c = cell(2,nufiles);
for ii = 1:numfiles
c{1,ii} = import x data from file ii
c{2,ii} = import y data from file ii
end
plot(c{:})
A structure, on the other hand
s.('test001').x = ...
s.('test001').y = ...
Use eval:
eval(sprintf('%s = struct(''x'',''y'',''z'');',casename(12:18)));
Edit: apologies, forgot the sprintf.
I am getting an error when running matlab code. Here I am trying to use one of the outputs of previous code as input to my new code.
??? Reference to non-existent field 'y1'.
Can anyone help me?
A good practice might be to check if the field exists before accessing it:
if isfield( s, 'y1' )
% s.y1 exists - you may access it
s.y1
else
% s.y1 does not exist - what are you going to do about it?
end
To take Edric's comment into account, another possible way is
try
% access y1
s.y1
catch em
% verify that the error indeed stems from non-existant field
if strcmp(em.identifier, 'MATLAB:nonExistentField')
fprintf(1, 'field y1 does not exist...\n');
else
throw( em ); % different error - handle by caller?
end
end
Have you used the command load to load data from file(s)?
if yes, this function overwrite your current variables, therefore, they become non-existent, so when you call, it instead of using:
load ('filename');
use:
f=load ('filename');
now, to refer to any variable inside the loaded file use f.varname, for
example if there is a network called net saved within the loaded data you may use it like:
a = f.net(fv);
I would first explain my situation and then give the solution.
I first save a variable op, it is a struct , its name is coef.mat;
I load this variable using coef = load( file_path, '-mat');
In a new function, I pass variable coef to it as a parameter, at here, the error Reference to non-existent field pops out.
My solution:
Just replace coef with coef.op, then pass it to the function, it will work.
So, I think the reason behind is that: the struct was saved as a variable, when you use load and want to acess the origin variable, you need point it out directly using dot(.) operation, you can directly open the variable in Matlab workspace and find out what it wraps inside the variable.
In your case, if your the outputs of previous code is a struct(It's my guess, but you haven't pointed out) and you saved it as MyStruct, you load it as MyInput = load(MyStruct), then when use it as function's parameter, it should be MyInput.y1.
Hops it would work!
At first load it on command window and observe the workspace window. You can see the structure name. It will work by accessing structure name. Example:
lm=load('data.mat');
disp(lm.SAMPLE.X);
Here SAMPLE is the structure name and X is a member of the structure