-- display all pythagorean triplets until n
pyth n = [(x,y,z)|x<-[1..n],y<-[x..n],z<-[x..n], x^2+y^2==z^2]


-- signum if get 0, standardsize as 0, other number is 1

signum 0 = 0
signum n = 1

-- write a program to read a list of tuples from the user of the form
-- [(1,"sam",25),(2,"john",24),(3,"mary",26)] and display the list of the form
-- [(1,25),(2,24),(3,26)]

mydisplay xs = [(x,z)|(x,y,z)<-xs]

-- write a program to read a list of tuples from the user of the form
-- [(2,4),(1,6),(0,3)] and produce the output
-- [8,6,0]

myprods xs = [(x*y)|(x,y)<-xs]

-- check if the list is sorted in ascending

pairup xs = zip xs (tail xs)
checkorder xs = and[(x<y)| (x,y)<-pairup xs ]

-- dot product
dotpro xs ys = sum [(x*y)|(x,y)<-zip xs ys]