# Reduce computational time for nested for loops

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EldaEbrithil on 18 Jun 2021
Commented: EldaEbrithil on 28 Jun 2021
Hi all
I wondered how could I reduce computational time for this for loop:
for i=1:length(Lungh)
for j=i:length(Largh)
for k=1:length(T)
for w=1:length(Delta)
for av=1:length(A_deg_prua_verticale)
for h=1:length(H)
for b=1:length(B)
for ti=1:length(t)
if abs(CB(i,j,k,w)>0)
if Largh(j)<Lungh(i)
if T(k)<Lungh(i)
L_cb(i)=Lungh(i);
Larg_cb(j)=Largh(j);
T_cb(k)=T(k);
Delta_cb(w)=Delta(w);
H_triangolo(k,av)=(T_cb(k))*tand(A_deg_prua_verticale(av));
Aw_d(i,k,av)=(L_cb(i)-H_triangolo(k,av))*Larg_cb(j)+(Larg_cb(j)* H_triangolo(k,av)/2);
Awc(i,k,av)=2*Aw_d(i,k,av);
Cw(i,j,k,av)= Aw_d(i,k,av)/(L_cb(i)*Larg_cb(j));
Zc(i,j,k,w,av)=T_cb(k)/(1+(CB(i,j,k,w)/Cw(i,j,k,av)));
Ix_demihull(i,j,k,w,av)=(W_tonn(w)/(2*gamma))*((Cw(i,j,k,av)^2)*...
(Larg_cb(j)^2))/(11.4*CB(i,j,k,w)*T_cb(k));
Ix_upper(j,h,ti,b)=(B(b)-2*Larg_cb(j))*(((t(ti)^3)/3)+t(ti)*H(h)^2-H(h)*t(ti)^2);
Ix(i,j,k,w,av,h,ti,b)=2*Ix_demihull(i,j,k,w,av)+Ix_upper(j,h,ti,b);
ZG(j,k,h,ti,b)=((Largh(j)*H(h)^2)-(Largh(j)*T_cb(k)^2)+(B(b)*(H(h)^2)/2)-B(b)*(H(h)^2+t(ti)^2-2*H(h)*t(ti))/2-(Largh(j)*H(h)^2)+...
((Largh(j)*T_cb(k)^2)+2*Largh(j)*(H(h)-t(ti)-T_cb(k))+(2*((B(b)/2)-Largh(j))*t(ti)));
Iy(i,j,k,w,av)=0.07*(Cw(i,j,k,av)/9.81)*W_tonn(w)*L_cb(i)^2;
Delta_Iy(i,j,k,av)=0.055*(gamma/9.81)*(Larg_cb(j)^2)*...
(L_cb(i)^3)*(Cw(i,j,k,av)^2)/((3-2*Cw(i,j,k,av))*(3-Cw(i,j,k,av)));
if Zc(i,j,k,w,av)<ZG(j,k,h,ti,b)&&Zc(i,j,k,w,av)>0&&ZG(j,k,h,ti,b)>0&&ZG(j,k,h,ti,b)<H(h)&&Zc(i,j,k,w,av)<H(h)
Z_C(i,j,k,w,av)=Zc(i,j,k,w,av);
Z_G(j,k,h,ti,b)=ZG(j,k,h,ti,b);
end
R(i,j,k,w,av)=(Cw(i,j,k,av)^2)*(L_cb(i)^2)/(14*CB(i,j,k,w)*T_cb(k));
H_L(i,j,k,w,av,h,ti,b)=R(i,j,k,w,av)+Z_C(i,j,k,w,av)-Z_G(j,k,h,ti,b);
kd(j,b)=((B(b)/2)-Largh(j))+(Largh(j)/2);
GM(i,j,k,w,av,h,ti,b)=(2*gamma*(Ix_demihull(i,j,k,w,av)+(kd(j,b)^2)*...
(Aw_d(i,k,av)))/(W_tonn(w)))+Z_C(i,j,k,w,av)-Z_G(j,k,h,ti,b);
if GM(i,j,k,w,av,h,ti,b)>0&&H_L(i,j,k,w,av,h,ti,b)>0
T_teta(i,j,k,w,av,h,ti,b)=(1/(2*pi))*(sqrt(Ix(i,j,k,w,av,h,ti,b)/(W_tonn(w)*GM(i,j,k,w,av,h,ti,b)))) ;
T_p(i,j,k,w,av,h,ti,b)=2*pi*sqrt((Iy(i,j,k,w,av))/(W_tonn(w)*H_L(i,j,k,w,av,h,ti,b)));
T_heaving(i,k,w,av)=2*pi*sqrt(W_tonn(w)/(9.81*gamma*Awc(i,k,av)));
if T_teta(i,j,k,w,av,h,ti,b)>0.2
T_teta_finale(i,j,k,w,av,h,ti,b)=T_teta(i,j,k,w,av,h,ti,b);
T_p_finale(i,j,k,w,av,h,ti,b)=T_p(i,j,k,w,av,h,ti,b);
T_heaving_finale(i,k,w,av)=T_heaving(i,k,w,av);
end
end
end
end
end
end
end
end
end
end
end
end
end
where length(Lungh) = 6, length(Largh)=9, length(T)=5, length(Delta)=7, length(A_deg_prua_verticale)=9, length(H)=11, length(B)=3, length(t)=3
Thank you for the help
Regards!

Sharmin Kibria on 25 Jun 2021
Hi,
You can definitely speed up the process by vectorization.
Replacing the loops with vectorized solution can speed up the computation.
Thanks
Sharmin
EldaEbrithil on 28 Jun 2021
Thank you very much Sharmin!

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