getting y1(i)=traj​ectory(x1(​i),v0,thet​a) presents an error

x=0;

y=4;

v0=80;

theta=50:10:90;

g=9.8;

disp('part a')

% a) and b)

fprintf("Theta(d)\t height(m)\t Range(m)\n");

for t = 1:length(theta)

ph=get_maxheight(v0,theta(t));

R=get_Range(ph,theta(t));

fprintf("%.2f \t\t %.2f\t\t %.2f\n",theta(t),ph,R);

x1=x:1:R;

y1=zeros(length(x1));

for i=1:length(x1)

y1(i)=trajectory(x1(i),v0,theta(t));

end

plot(x1,y1)

title('Projectile path')

grid on

xlabel('x')

ylabel('y')

hold on

end

disp('part c')

% c)

x=0;

v0=80;

theta=45;

y=2:2:10;

fprintf("y(m)\t height(m)\t Range(m)\n");

for t = 1:length(y)

ph=get_maxheight(v0,theta);

R=get_Range(ph,theta);

fprintf("%.2f \t\t %.2f\t\t %.2f\n",y(t),ph,R);

end

%%%% Range Function %%%

function R=get_Range(mh,theta)

R=(mh*4)/tand(theta);

end

%%% Max Heigt Function %%%

function mh=get_maxheight(v0,theta)

mh=(v0*v0*sind(theta)*sind(theta))/(2*9.8);

end

%%% Theta Function %%%

function theta=get_theta()

theta=input('Enter angle of projection(theta): ');

end

%%% V0 Function %%%

function v0=get_v0()

v0=input('Enter initial velocity(v0): ');

end

%%% X Function %%%

function x=get_x()

x=input('Enter horizontal position(x): ');

end

%%% Y Function %%%%

function y=get_y()

y=input('Enter vertical position(x): ');

end