Created
March 31, 2016 18:06
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symbolic differentiation is SO EASY in haskell!
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| -- i mean, this is basically just a high school formula sheet | |
| -- that happens to also be valid haskell | |
| -- (we're differentiating against "Symbol") | |
| diff (Symbol) = Val 1 | |
| diff (Neg x) = Neg (diff x) | |
| diff (Add x y) = Add (diff x) (diff y) | |
| diff (Mul x y) = Add (Mul (diff x) y ) (Mul x (diff y)) | |
| diff (Sub x y) = diff (Add x (Neg y)) | |
| diff (Pow x (Val n)) = Mul (Val n) (Pow x (Val (n - 1) ) ) | |
| diff (Div x y) = diff (Mul x (Pow y (Val (-1)) ) ) | |
| diff (Exp x) = Mul (Exp x) (diff x) | |
| diff (Sin x) = Mul (Cos x) (diff x) | |
| diff (Cos x) = Neg (Mul (Sin x) (diff x) ) | |
| diff (Fxn xs y) = Mul (Fxn (xs ++ "\'") y) (diff y) | |
| -- most of this stuff is written in polish notation, but if we want to be even clearer | |
| -- we can write it in infix notation: | |
| diff (x `Mul` y) = ((diff x) `Mul` y ) `Add` (x `Mul` (diff y)) |
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Do you have the part for the codes Add, Pow and Mul?