Проблема с вычислением

[oban11]

program lab7part2;
uses crt;
const t=1e-9;
var z:array[1..15] of real;
    x,xn,xk,y,yn,yk,hx,hy,ch,zn,cosec,f:real;
    ki,i:byte;
    ks:word;
BEGIN
clrscr;
ks:=0;
write('Vvedite xn=');
readln(xn);
write('Vvedite xk=');
readln(xk);
write('Vvedite Hx=');
readln(Hx);
write('Vvedite yn=');
readln(yn);
write('Vvedite yk=');
readln(yk);
write('Vvedite Hy=');
readln(Hy);
write('Vvedite kol-vo elementov massiva Z ki=');
readln(ki);
For i:=1 to ki do
begin
writeln('Vvedite Z[',i,']');
readln(z[i]);
end;
while x<xk+t do
begin
x:=xn;
while y<yk+t do
begin
y:=yn;
for i:=1 to ki do
begin
inc(ks);
writeln(ks:2,' x=',x:6:2,' y=',y:6:2,' z[',i,']=',z[i]:6:2);
ch:=cos(y);
if ch>-t then
begin
ch:=sqrt(ch)+exp(z[i]);
cosec:=sin(y+z[i]);
if abs(cosec)>t then
begin
cosec:=1/sin(y+z[i]);
if abs(cosec)>t then
begin
f:=sin(x)/cosec;
zn:=exp(cos(z[i])*ln(5))+exp(y*ln(x))+z[i];
if abs(zn)>t then
begin
f:=ch/zn+f;
writeln('f=',f:12:6);
end
else
writeln('f - no exist delenie na 0')
end
else
writeln('f - no exist delenie na 0')
end
else
writeln('f - no exist delenie na 0')
end
else
writeln('f - no exist podkorennoe virazhenie <0');
x:=x+hx;
y:=y+hy
end;
end;
end;
readkey
END.

[oban11]

удалите тему случ 2 сделал