Quadratic equation in Scratch

Scratch is a graphical language, the print-screen contains the actual information about the program, source text is only a transcription. This example features the usage of text input in Scratch, which is done with command ask "..." and wait. This command makes the sprite “say” the associated message (used as prompt) and displays an input window below the sprite. Once the information is entered, is can be accessed through predefined variable answer, which is copied to local variables before entering next values.

ask "A = ?" and wait
set A to answer
if A = 0
   say "Not a quadratic equation"
else
   ask "B = ?" and wait
   set B to answer
   ask "C = ?" and wait
   set C to answer
   set D to B*B + (-4)*A*C
   set re to B/(-2*A)
   if D = 0
      say join ("x = " re)
   else
      set im to (sqrt of (abs of D)) / (2*A)
      if D > 0
         say join (join ("x1 = " (re+im)) join (", x2 = " (re-im)))
      else
         say join (join ("x1 = (" join (re join (", " im))) join ("), x2 = (" join (re join (", -" join (im ")")))))

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