J'ai tranformé mon programme de la manière suivante (voir ci-après). J'ai spécifié le type de la plupart des fonctions. Ca marche mieux, mais l'écriture est sérieusement plus lourde! J'ai encore un problème: courbe = defaultPlotLines { plot_lines_values = [[ (Point a b) | (a,b) <- ps]], plot_lines_style = solidLine lineWidth 0 0 1 } donne l'erreur: Couldn't match expected type `Double' against inferred type `Float' In the first argument of `Point', namely `a' In the expression: (Point a b) In the expression: [(Point a b) | (a, b) <- ps] en effet Point prend des doubles. Je n'ai pas trouvé de fonctions de conversion Float vers Double... Merci! Corentin *module Lagrange where* *nombre_points :: Integer nombre_points = 7* *-- creation d'une liste exluant i list :: Integer -> [Integer] list i = filter (/=i) [0..nombre_points-1] * *-- un terme du polynôme de Lagrange --un_terme :: Float -> Integer -> Integer -> Float un_terme t j i = (t - i_f)/(j_f - i_f) where i_f = fromInteger i j_f = fromInteger j* *--produit des termes pour obtenir le polynôme d'un point les_termes t j = map (un_terme t j) (list j) poly t j = product (les_termes t j)* * * *--blend (a,t) = a(0) * (poly t 0) + a(1) * (poly t 1) + a(2) * (poly t 2) + a(3) * (poly t 3) + -- a(4) * (poly t 4) + a(5) * (poly t 5) + a(6) * (poly t 6)* *--t est le paramètre du polynôme, a sera la coordonnée (x ou y). blend_un_point :: Float -> (Integer -> Float) -> Integer -> Float blend_un_point t a numero_point = a(numero_point) * (poly t numero_point) blend_les_points t a = map (blend_un_point t a) [0..6]* *blend :: (Integer -> Float, Float) -> Float blend (a,t) = sum (blend_les_points t a)* *-- Sample points xy = [(-4.0,0.0), (-1.0,1.0), (-3.0,3.0), (0.0,4.0), (3.0,3.0),(1.0,1.0),( 4.0,0.0)]* *--creation des fonctions x et y x :: Integer -> Float x pos = fst (xy !! pos_Integer) where pos_Integer = fromInteger(pos) y :: Integer -> Float y pos = snd (xy !! pos_Integer) where pos_Integer = fromInteger(pos)* *-- Blend the sample points for some given u: bx :: Float -> Float bx(u) = blend(x,u)* *by :: Float -> Float by(u) = blend(y,u)* *-- Take m+1 values for u, from 0 to nombre_points, equally spaced: us :: Integer -> [Float] us m = map (/mf) [0..6*mf] where mf = fromInteger m* *-- For* *m = 50* *-- we get us(m)=[0.0, 0.125, 0.25, 0.375, 0.5, 0.625, 0.75, 0.875, 1.0].* *-- Now get a list of points for the above values of the parameter:* *xs = map bx (us(m)) ys = map by (us(m))* *-- Running this, we get, where I've rounded the results to 2 digits: -- -- xs = [0.00, 0.38, 0.75, 1.1, 1.5, 1.9, 2.3, 2.6, 3.0] -- ys = [0.00, 0.46, 1.00, 1.7, 2.3, 2.8, 3.1, 3.2, 3.0]* *-- Finally, get a list of pairs (x,y), i.e. a list of points:* *ps = zip xs ys* *-- In this example, running "ps" we get, after rounding, the points: -- -- [(0, 0), (0.38, 0.46), (0.75, 1), (1.1, 1.7), -- (1.5, 2.3), (1.9, 2.8), (2.3, 3.1), (2.6, 3.2), (3, 3)] -- -- Now plot lines joining these points to get an approximation of the curve *