Using logically indexed vector in a loop to create another vector
2 vues (au cours des 30 derniers jours)
Afficher commentaires plus anciens
I have a vector `p=[-3 -2 -1 0 1 2 3]`, and an expression for and for ; and c have values. I want to create a vector . How to write a `for` loop to implement the above statement? The code I wrote to implement the first part of the statement is
k=2; p=[-3 -2 -1 0 1 2 3]; c=1; a=5; b=9;
L=logical(p);
p(L);
for K = 1:numel(L)
if L(K) < 1
L(K) = a*exp(1i*K*k)+b*exp(-1i*K*k)
end
end
However, it returns error "Complex values cannot be converted to logicals". Secondly, the output for p(L) doesn't have the value 0 in it. I did it with a direct way which is not convenient for large vectors.
psi_33 = a*exp(-1i*3*k)+b*exp(1i*3*k);
psi_22 = a*exp(-1i*2*k)+b*exp(1i*2*k);
psi_11 = a*exp(-1i*1*k)+b*exp(1i*1*k);
psi_0 = a+b;
psi_1 = c*exp(1i*k);
psi_2 = c*exp(1i*2*k);
psi_3 = c*exp(1i*3*k);
phi11=[psi_33,psi_22,psi_11,psi_0,psi_1,psi_2,psi_3];
0 commentaires
Réponses (2)
KSSV
le 28 Nov 2018
p=[-3 -2 -1 0 1 2 3] ;
phi = zeros(size(p)) ;
for i = 1:length(p)
if -3<p(i)<1
% phi(i) = your expression
elseif 1<=p(i)<=3
% phi(i) = your expression
end
end
4 commentaires
Andrei Bobrov
le 28 Nov 2018
Modifié(e) : Andrei Bobrov
le 28 Nov 2018
a = 5;
b = 9;
c = 1;
p = (-3:3)';
k = 2;
out = psifun(a,b,c,k,p);
here psifun - function:
function out = psifun(a,b,c,k,p)
a = [a;c];
b = [b;0];
ii = (p >= 1) + 1;
x = 1i*k.*p;
out = a(ii).*exp(x) + b(ii).*exp(-x);
end
0 commentaires
Voir également
Catégories
En savoir plus sur Logical dans Help Center et File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!