Display a linear combination: Difference between revisions

Content added Content deleted

Inline

@@ Line 733: / Line 733: @@
 [-1, -2, 0, -3]  ->  -e(1) - 2*e(2) - 3*e(4)
 [-1]             ->  -e(1)</pre>
+=={{header|Haskell}}==
+<lang haskell>import Text.Printf (printf)
+linearForm :: [Int] -> String
+linearForm = strip . concat . zipWith term [1..]
+  where
+    term :: Int -> Int -> String
+    term i c
+      | c == 0  = printf ""
+      | c == 1  = printf " + e(%d)" i
+      | c > 0   = printf " + %d*e(%d)" c i
+      | c == -1 = printf " - e(%d)" i
+      | c < 0   = printf " - %d*e(%d)" (-c) i
+    strip str = case str of
+      ' ':'+':' ':s -> s
+      ' ':'-':' ':s -> '-':s
+      ""            -> "0"
+      s             -> s</lang>
+Testing
+<lang haskell>coeffs :: [[Int]]
+coeffs = [ [1, 2, 3]
+         , [0, 1, 2, 3]
+         , [1, 0, 3, 4]
+         , [1, 2, 0]
+         , [0, 0, 0]
+         , [0]
+         , [1, 1, 1]
+         , [-1, -1, -1]
+         , [-1, -2, 0, -3]
+         , [-1] ]</lang>
+<pre>λ> mapM_ (print . linearForm) coeffs
+"e(1) + 2*e(2) + 3*e(3)"
+"e(2) + 2*e(3) + 3*e(4)"
+"e(1) + 3*e(3) + 4*e(4)"
+"e(1) + 2*e(2)"
+"0"
+"0"
+"e(1) + e(2) + e(3)"
+"-e(1) - e(2) - e(3)"
+"-e(1) - 2*e(2) - 3*e(4)"
+"-e(1)"</pre>
 =={{header|J}}==