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Can I store a function including multiple variable?

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chia ching lin
chia ching lin on 18 Oct 2020
Commented: Walter Roberson on 24 Oct 2020
Hi,
Im new to matlab, is it able to store function including multiple variable which still can be used? Something like this
x=linspace(1,10,100);
t=linspace(1,5,50);
f=@(x,t,theta) sin(x+t(a)+theta)
for i=1:10
state{i}=f(:,:,i);
end
where i expect that (but it is not)
state={sin(x+t(a)+1) sin(x+t(a)+2) sin(x+t(a)+3) ... sin(x+t(a)+10)}
so i can used a for loop on t to make a annimation like this
for a=1:length(t)
for b=1:length(state)
plot(x,state{b}(a));
end
end
Is it possible to do something like above or Im using the wrong function?

  3 Comments

Prudhvi Peddagoni
Prudhvi Peddagoni on 22 Oct 2020
can you elaborate more on what you are trying to do?
what is the variable a in the anonymous function?
what should the variable state contain and what should be it's length?
chia ching lin
chia ching lin on 22 Oct 2020
I'm trying to make a wave propagating and will change it's phase at the source by time, also consider the retarded potential. The equation suppose to be
E=E0*exp(w(t-x/c)+theta)*u(t-x/c);
where the E0 = amplitude, w = angular frequency, t = time, x = propagate direction, c = 3*10^8, theta = phase, u = step function.
The problem is that if I change the phase at the souce, the whole wave will change. If it only change phase at source, the wave wouldn't look like a a sine or cosine wave when time ends.
The length of state is how much times the phase change. I set the phase change with the time ,so if the time length is 50, the length of the state will be 50. It need to be a variable.
The a is the length of the time , I want all the function in state can run in one for loop changing by time.

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Answers (2)

Steven Lord
Steven Lord on 22 Oct 2020
You can't call a function handle using :. If you want the anonymous function to "remember" and use the values of x and t that you've defined in the workspace, you can do that.
x = 1:10;
y = 2;
f = @(theta) y*sin(x+theta);
z1 = f(7)
% check
z2 = 2*sin(8:17)

  1 Comment

chia ching lin
chia ching lin on 22 Oct 2020
Tks for answering, but this isn't quite I want. I know its able to used multiple variable in function handle, but it is only 'one' function for me to used. Is it able to have the same result as below?
%example
f=sin(x*t+theta); % function I used
x=[1 2 3 4 5 6 7 8 9 10]; % spactial distribution % will remain unchange in for loop
t=[1 2 3 4 5]; % time
theta=[1 2 3 4 5]; % phase change by time (will be same length as time)
first, I would like to do something to this function to made it :
F=[ sin(x*t+1) sin(x*t+2) sin(x*t+3) sin(x*t+4) sin(x*t+5)];
so I can call the function for example: F{1}=sin(x*t+1)
next, the function in F need to move together by time :
for b=1:length(theta) % F{1},F{2},F{3},F{4},F{5}
for a=1:length(t) % time change
A=F{b}(a); % (a) is suppose to be the time change, but I don't know how to do with it
end
end
The wave function will times a step function in my code at last, so I cant change the order of my code, it need to be step by step like that.
The length of t and theta will be greater then 1000, so I can't type the function one by one.

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Walter Roberson
Walter Roberson on 22 Oct 2020
for i=1:10
state{i}=@(x,t)f(x,t,i);
end
Note that this will be a cell array of function handles and if you wanted an array of results you would need to cellfun
cellfun(@(F) F(x, y), state)

  2 Comments

chia ching lin
chia ching lin on 24 Oct 2020
What is the y in the cellfun? And what is F stands for in the code?
How can I fix my code? This is what I get now. I'm not quite sure the usage of the cellfun, need more help.
x=linspace(0,10,100);
t=linspace(0,5,50);
phase=0:pi/3:2*pi;
for i=1:5
state{i}=@(x,t) sin(x.*t+phase(i));
end
C=cellfun(@(F) F(x,t),state);
Thanks.

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