Use of nested loop

I wrote a program using nested loop. It shows error "The following error occurred converting from sym to double:

DOUBLE cannot convert the input expression into a double array."

code:

clear all
clc
format longEng
syms z 
phi=(pi/180)*39;
delta=(pi/180)*26;
gma=18.4;
h=4;
h1=1.9185831159674030330446155463409;
h2=0.088292704979722319631609763226466;
L=h+h1+h2;
beta=1;
alfa=1;
z1=z-h;
z2=z-h-h1;
Ra1=-1; 
Ra2=-(alfa*(z2/h2))^0.5;
Rp1=3*(beta*(1-(z1/(h1))))^0.5;
Rp2=3*(alfa*(z2/h2))^0.5;

delma1=0.5*(1-Ra1)*delta;
delma2=-0.5*(1-Ra2)*delta;
delmp1=0.5*(Rp1-1)*delta;
delmp2=0.5*(Rp2-1)*delta;

ka1=(2*cos(phi)^2)/(cos(phi)^2*(1+Ra1)+cos(delma1)*(1-Ra1)*(1+sqrt((sin(phi+delma1)*sin(phi))/cos(delma1)))^2);
ka2=(2*cos(phi)^2)/(cos(phi)^2*(1+Ra2)+cos(delma2)*(1-Ra2)*(1+sqrt((sin(phi+delma2)*sin(phi))/cos(delma2)))^2);
kp11=(2*cos(phi)^2)/(cos(phi)^2*(1+Rp1)+cos(delmp1)*(1-Rp1)*(1+sqrt((sin(phi+delmp1)*sin(phi))/cos(delmp1)))^2);
kp12=1+0.5*(Rp1-1)*((cos(phi)^2/(cos(delmp1)*(-sqrt((sin(phi+delmp1)*sin(phi))/cos(delmp1))+1)^2))-1);
kp21=(2*cos(phi)^2)/(cos(phi)^2*(1+Rp2)+cos(delmp2)*(1-Rp2)*(1+sqrt((sin(phi+delmp2)*sin(phi))/cos(delmp2)))^2);
kp22=1+0.5*(Rp2-1)*((cos(phi)^2/(cos(delmp2)*(-sqrt((sin(phi+delmp2)*sin(phi))/cos(delmp2))+1)^2))-1);
i=0;
for z=0:0.02:L
    i=i+1;
if(z<h)
    k1(i)=ka1;
    k2(i)=0;
elseif(z>=h && z<(h+h1))
    k1(i)=ka1;
 for Rp1=0:0.02:3
     if Rp1<1
         k2(i)=kp11;
     else
         k2(i)=kp12;
     end
 end
else
    for Rp2=0:0.02:3
     if Rp1<1
         k1(i)=kp21;
     else
         k1(i)=kp22;
     end
    end
 k2(i)=ka2;       
end   
end

z=0:0.02:L;

subplot(2,1,1);
plot(z,k1,z,k2)
grid on

Answer 1

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Read about function double