How to only show the last 10 iterations inside of this For Loop

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Greg McCurry
Greg McCurry 2018-11-20
回答： KSSV 2018-11-20
h = 0.02;
t = 0:h:20;
N = length(t);
x = zeros(N,1);
y = zeros(N,1);
z = zeros(N,1);
e = @(t, x, y, z) y;
f = @(t, x, y, z) z;
g = @(t, x, y, z) -0.25*(x*z+2*y*y);
x(1) = 0;
y(1) = 0;
z(1) = (2*exp(5/2))/9;
for i = 1:(N-1)
K1 = h * e( t(i) , x(i) , y(i) , z(i));
L1 = h * f( t(i) , x(i) , y(i) , z(i));
M1 = h * g( t(i) , x(i) , y(i) , z(i));
K2 = h * e(t(i) + 1/2*h, x(i)+1/2*K1 , y(i)+1/2*L1 , z(i)+1/2*M1);
L2 = h * f(t(i) + 1/2*h, x(i)+1/2*K1 , y(i)+1/2*L1 , z(i)+1/2*M1);
M2 = h * g(t(i) + 1/2*h, x(i)+1/2*K1 , y(i)+1/2*L1 , z(i)+1/2*M1);
K3 = h * e(t(i) + 1/2*h, x(i) + 1/2*K2 , y(i) + 1/2*L2 , z(i) + 1/2*M2);
L3 = h * f(t(i) + 1/2*h, x(i) + 1/2*K2 , y(i) + 1/2*L2 , z(i) + 1/2*M2);
M3 = h * g(t(i) + 1/2*h, x(i) + 1/2*K2 , y(i) + 1/2*L2 , z(i) + 1/2*M2);
K4 = h * e( t(i)+h , x(i)+K3 , y(i)+L3, z(i)+M3);
L4 = h * f( t(i)+h , x(i)+K3 , y(i)+L3, z(i)+M3);
M4 = h * g( t(i)+h , x(i)+K3 , y(i)+L3, z(i)+M3);
x(i+1) = x(i)+1/6*(K1+2*K2+2*K3+K4);
y(i+1) = y(i)+1/6*(L1+2*L2+2*L3+L4);
z(i+1) = z(i)+1/6*(M1+2*M2+2*M3+M4);
end
Answer_Matrix = [t' x y z];
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Greg McCurry
Greg McCurry 2018-11-20
编辑：Greg McCurry 2018-11-20
Edited** Code shown below and in original question now
h = 0.02;
t = 0:h:20;
N = length(t);
x = zeros(N,1);
y = zeros(N,1);
z = zeros(N,1);
e = @(t, x, y, z) y;
f = @(t, x, y, z) z;
g = @(t, x, y, z) -0.25*(x*z+2*y*y);
x(1) = 0;
y(1) = 0;
z(1) = (2*exp(5/2))/9;
for i = 1:(N-1)
K1 = h * e( t(i) , x(i) , y(i) , z(i));
L1 = h * f( t(i) , x(i) , y(i) , z(i));
M1 = h * g( t(i) , x(i) , y(i) , z(i));
K2 = h * e(t(i) + 1/2*h, x(i)+1/2*K1 , y(i)+1/2*L1 , z(i)+1/2*M1);
L2 = h * f(t(i) + 1/2*h, x(i)+1/2*K1 , y(i)+1/2*L1 , z(i)+1/2*M1);
M2 = h * g(t(i) + 1/2*h, x(i)+1/2*K1 , y(i)+1/2*L1 , z(i)+1/2*M1);
K3 = h * e(t(i) + 1/2*h, x(i) + 1/2*K2 , y(i) + 1/2*L2 , z(i) + 1/2*M2);
L3 = h * f(t(i) + 1/2*h, x(i) + 1/2*K2 , y(i) + 1/2*L2 , z(i) + 1/2*M2);
M3 = h * g(t(i) + 1/2*h, x(i) + 1/2*K2 , y(i) + 1/2*L2 , z(i) + 1/2*M2);
K4 = h * e( t(i)+h , x(i)+K3 , y(i)+L3, z(i)+M3);
L4 = h * f( t(i)+h , x(i)+K3 , y(i)+L3, z(i)+M3);
M4 = h * g( t(i)+h , x(i)+K3 , y(i)+L3, z(i)+M3);
x(i+1) = x(i)+1/6*(K1+2*K2+2*K3+K4);
y(i+1) = y(i)+1/6*(L1+2*L2+2*L3+L4);
z(i+1) = z(i)+1/6*(M1+2*M2+2*M3+M4);
end
Answer_Matrix = [t' x y z];

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回答（1 个）

KSSV
KSSV 2018-11-20
Check this exmple code:
N = 100 ; % loop count
i = 1:N ;
last10 = i(end:-1:end-10) ;
for i = 1:N
if any(ismember(i,last10))
fprintf('loop = %d\n',i);
end
end

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