Running a summation for a loop for different values of N.

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Christopher
Christopher 2013-6-13
Hello,
I have written a function that basically uses a for loop to solve a summation from 1 to N values. I am trying to run this function for different values of N and plot the results on the same plot to compare convergence. So I would like to run the function for N=5, N=20, and N=100 and plot. What is the best way to run this function to solve for each of the different values of N and store them, so they can be plotted together? I was thinking something like:
a=1:N
b=2
c=4
for N=5
e=func(a,b,c,N)
end
for N=20
f=func(a,b,c,N)
end
for N=100
g=func(a,b,c,N)
end
plot(a,e,a,f,a,g)
Where a is length N and will be the x-axis of the plot. Is there a more efficient or better way to do this?

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采纳的回答

Jan
Jan 2013-6-13
N = [5, 20, 100];
result = zeros(1, length(N)); % Or what ever matchs your output
for iN = 1:length(N)
result(iN) = func(a, b, c, N(iN))
end
plot(a, result(1), a, result(2), a, result(3));
Perhaps you want something like:
result(iN, :) = func(a, b, c, N(iN))
% or
result(:, iN) = func(a, b, c, N(iN))
with a corresponding pre-allocation and modifications in the PLOT line.
  1 个评论
Christopher
Christopher 2013-6-14
编辑：Christopher 2013-6-14
Jan,
When I input this it solves for the first value of N (5), but then when it tries to solve for the 2nd value of N (20) I get this error:
??? In an assignment A(I) = B, the number of elements in B and I must be the same.
Any ideas on what is causing this? The code is listed below:
function [LLT_solver] = LLT_run
global b N c a alpha alphaoL e AR
type=2 % read the input file using read_inp1.m
if type == 2
read_inp_type2;
N = [5, 20, 100];
result = zeros(1, length(N)); % Or what ever matchs your output
for iN = 1:length(N)
result(iN) = LLT_type2(b,N(iN),c,a,alpha,alphaoL,e,AR)
% LLT_type2(b,N,c,a,alpha,alphaoL,e,AR);
end
end
The function LLT_Type2 is:
function[An,CL,delta,CDi,Gamma,Cl]=LLT_type2(b,N,c,a,alpha,alphaoL,e,AR)
b;
N;
c=(c*ones(1,N))';
a=(a*ones(1,N))';
alpha=(alpha*ones(1,N))';
alphaoL=(alphaoL*ones(1,N))';
e=(e*ones(1,N))';
n=1:N; % n rows
theta=(n.*pi/(N+1))'; % theta values
y0=-b/2*cos(theta); % y values for each theta
RHS=(alpha+e-alphaoL)/180*pi; % Solving RHS
% Finding IC matrix to solve for An's
IC = zeros(N);
for l = 1:N;
for m = 1:N;
IC(l,m) = (4*b/a(l)/c(l)+m/sin(theta(l)))*sin(m*theta(l));
end
end
format long
An=IC\RHS
CL=An(1)*pi*AR
x=((n.*((An'./An(1))).^2));
delta=x(2:N);
format short
delta=sum(delta)
CDi=(CL^2/(pi*AR))*(1+delta)
% calculation of the vorticity Gamma on the wing
for i=1:N,
Gamma(i)=2*b*sum(An(:).*sin((1:N)*theta(i))');
end;
Gamma
Cl=(2*Gamma)./c'
plot(y0,Cl); ylabel('Cl / Vinf');
Thank you for your help. It's greatly appreciated.

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更多回答（1 个）

Andrei Bobrov
Andrei Bobrov 2013-6-13
编辑：Andrei Bobrov 2013-6-13
N = [5 20 100]
b = 2;
c = 4;
f = arrayfun(@(x)[(1:x)',reshape(func((1:x)',b,c,x),[],1)],N,'un',0);
plot(f{:});

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