i want to use goto to jump from third line to eighth line.

if(i~=4)
  if (dx/yg(i))<tand(sia)
    goto X
  else
    P(i-1)=0
  end
else
  X
end

Answer 1

[dpb]

if (i==4)|((dx/yg(i))<tand(sia))
  X
else
  P(i-1)=0
end

or

if (i~=4)&((dx/yg(i))>=tand(sia))
  P(i-1)=0
else
  X
end

[dpb]

BTW, if had rest of loop over i, it's quite possible/probable(?) could eliminate it and vectorize the expression.