Heron formula

We can use Heron formula to practice how to create procedures and develop simple algorithms. Here are presented a few stages of developing the Heron procedure.

heron1 := proc(a,b,c)

begin

 s := (a + b + c)/2;

 sqrt(s*(s - a)*(s - b)*(s - c))

end:

heron1(3,4,5)

6

heron2 := proc(a,b,c)

begin

   if a<0 or b<0 or c<0 then

      print("This is not a real triangle")

   else

      s := (a + b + c)/2;

      sqrt(s*(s - a)*(s - b)*(s - c))

   end

end:

heron2(3,5,9)

    
heron3 := proc(a,b,c)

begin

   if a<0 or b<0 or c<0 or (a-b-c)*(b-a-c)*(c-a-b)>0

   then

      print("This is not a real triangle.")

   else

      s := (a + b + c)/2;

      sqrt(s*(s - a)*(s - b)*(s - c))

   end

end:

heron3(-1,1,1)

"This is not a real triangle."

heron := proc(a,b,c)

   local s;

begin

   if a<0 or b<0 or c<0 or (a-b-c)*(b-a-c)*(c-a-b)>0

   then

      print("This is not a real triangle")

   else

      s := (a + b + c)/2;

      return(sqrt(s*(s - a)*(s - b)*(s - c)));

   end

end:

heron(-1,1,2)

"This is not a real triangle."

© Miroslaw Majewski, Abu Dhabi,  Update  26-10-2004