// comments noted, once the while function gets actived the program loops this only occurs when the shape does not fit with the values 1, 2 and 3
//I used for statement protect the input from deleting it self
// I don't exactly know why the function work...help did extensive reading none of the lit has anything on the exactly how to push out a result
// I activated the will statement and looped the program. it works brings me back to the start, but here is the real problem
// once i try to work the code with a correct statement the program seems to crash or give a error in the code before the loop.
// or a error in the code inside the loop.
//please could you please highlight the best way forward?
clc
disp("which shape you want to calcalute the area or perimeter")
disp("Square(1),Circle(2),Triangle(3)")
for a=input("select your shape?")
end
pi4=(%pi/4);
  if a==1 then
    disp("square")
    for b=input("perimeter(1) or area(2)")
    end
    if b==1 then
        disp("perimeter")
        for x=input("size of side")
        end
        [d]=(x)
        d=x*4
        horner(d,x)
    elseif b==2
        disp("area")
        for c=input("size of side")
        end
        function e(c)=c^2
        endfunction
        horner(e)
    end
elseif a==2 then
    disp("circle")
    for f=input("perimeter(1) or area(2)")
    end
    if f==1 then
        disp("perimeter")
        for g=input("size of diameter")
        end
        function h(g)=g*pi4*4
        endfunction
    elseif f==2
        disp("area")
        for j=input("size of diameter")
        end
        function k(j)=pi4*j^2
        endfunction
    end
elseif a==3 then
    disp("triangle")
    for l=input("perimeter(1) or area(2)")
    end
    if l==1 then
        disp("perimeter")
        for m=input("size of base")
        end
        for n=input("size of height")
        end
        function o(m,n)=m+n((m^2)+(n^2))^0.5
        endfunction
    elseif l==2 then
        disp("area")
        for p=input("size of base")
        end
        for q=input("size of height")
        end
        function r(p,q)=0.5*p*q
        endfunction
    end
  end

while a<1 |a>3//loop happens when a does not get 1 or 2 or 3
    //loop i tried did not work so well "while a<>1 or a<>2 or a<>3"
    disp("which shape you want to calcalute the area or perimeter")
disp("Square(1),Circle(2),Triangle(3)")
for a=input("select your shape?");
end
pi4=(%pi/4);
  if a==1 then
    disp("square")
    for b=input("perimeter(1) or area(2)")
    end
    if b==1 then
        disp("perimeter")
        for c=input("size of side")
        end
        function d(c)=c*4
        endfunction
    elseif b==2
        disp("area")
        for c=input("size of side")
        end
        function e(c)=c**2
        endfunction
    end
elseif a==2 then
    disp("circle")
    for f=input("perimeter(1) or area(2)")
    end
    if f==1 then
        disp("perimeter")
        for g=input("size of diameter")
        end
        function h(g)=g*pi4*4
        endfunction
    elseif f==2
        disp("area")
        for j=input("size of diameter")
        end
        function k(j)=pi4*j^2
        endfunction
    end
elseif a==3 then
    disp("triangle")
    for l=input("perimeter(1) or area(2)")
    end
    if l==1 then
        disp("perimeter")
        for m=input("size of base")
        end
        for n=input("size of height")
        end
        function o(m,n)=m+n((m^2)+(n^2))^0.5
        endfunction
    elseif l==2 then
        disp("area")
        for p=input("size of base")
        end
        for q=input("size of height")
        end
        function r(p,q)=0.5*p*q
        endfunction
    end//here is a error no idea why??
  end
end// and here error