I wrote this program which has to multiply two matrixes but it says (empty list in tail), I guess my recurrence conditions are wrong but as a begginner, I don't realy see the problem, can you help me ? I think someone with enaugh experience will see the problem in 2 secondes.
multVecttt :: [Int]-> [Int] -> Int -- multiply a vector with a vector
multVecttt [][]=0
multVecttt [] _=0
multVecttt [a] [b]=a*b
multVecttt xs ys= (head xs) * (head ys) + multVecttt (tail xs) (tail ys)
multVectMat :: [Int]-> [[Int]] -> [Int]-- multiply a vector with a matrix using hadamard multiplication of matrixes
multVectMat [] [[a]]=[a]
multVectMat [][]=[]
multVectMat [] _=[]
multVectMat _ []=[]
multVectMat xs (ys: [[]]) = [multVecttt xs ys]
multVectMat xs yss= [multVecttt xs (head yss)] ++ multVectMat xs (tail yss)
multMatrix :: [[Int]] -> [[Int]] -> [[Int]]-- multiply two matrixes
multMatrix [][]=[]
multMatrix [][[a]]=[[a]]
multMatrix [[a]] [[b]]= [[a*b]]
multMatrix (xs: [[]]) yss = [multVectMat xs yss]
multMatrix xss yss = [multVectMat (head xss) (trans yss)] ++ multMatrix (tail xss) yss
trans:: [[Int]]-> [[Int]]-- return the transpose of a matrix
trans [[]]=[[]]
trans [[a],[b]]=[[a] ++ [b]]
trans xss=[(transHead xss)] ++ trans(transTail xss)
transHead:: [[Int]]->[Int]
transHead []=[]
transHead [[a],[b]]=[a] ++ [b]
transHead xss= [head(head xss)] ++ transHead (tail xss)
transTail:: [[Int]]-> [[Int]]
transTail []=[]
transTail xss= [tail(head xss)] ++ transTail(tail xss)
I wrote comments to make sure tou understand what are the functions doing
it compiles, but I have an execution error which is : Prelude.tail: empty list
