[clean-list] Troubles about Vectors

[Diederik van Arkel]

On Nov 19, 2003, at 5:46 PM, Alves da Silva Cruz Willer wrote:

> Hello Cleaners,
>  
> I've been working on a single DFT implementation but I've got in some 
> troubles regarding vectors. Clean returns a share error, wich I can't 
> understand and solve. The error message is something like this:
>  
> "some" demanded attribute cannot be offered by shared object.
>  

The "some" here is the '*' uniqueness attribute. In loop1 you are using 
x1 and
y1 twice in the definition thus they are shared and not unique as your 
type tries
to claim. Solution: either remove the uniqueness attribute or return x1 
and y1 from
loop2 thus removing the sharing eg.
...
	# (x1,y1,x2,y2) = loop2 i 0 m arg x1 y1 x2 y2
	= loop1 (i+1) m dir x1 y1 x2 y2

loop2 :: Int Int !Int !Real *{#Real} *{#Real} *{#Real} *{#Real} -> 
(*{#Real},*{#Real},*{#Real},*{#Real})
loop2 i k m arg x1 y1 x2 y2
	| k == m = (x1,y1,x2,y2)
...

Regards,

Diederik van Arkel

> The testing code follows below. Has someone know what could be wrong 
> with this code?
>  
> module test
> import StdEnv
>  
> Start = DFT 1 8 { 1.0 \\ i <- [1..8] } { 0.0 \\ i <- [1..8] }
> DFT :: !Int !Int *{#Real} *{#Real} -> (*{#Real},*{#Real})
> DFT dir m x1 y1
> #! m = size x1
> # x2 = { 0.0 \\ i <- [1..m] }
> # y2 = { 0.0 \\ i <- [1..m] }
> # (x2,y2) = loop1 0 m dir x1 y1 x2 y2
> | dir == 1 = ({ x/(toReal m) \\ x <-: x2},{ y/(toReal m) \\ y <-: y2})
> | otherwise = (x2,y2)
> where
>  loop1 :: Int !Int !Int *{#Real} *{#Real} *{#Real} *{#Real} -> 
> (*{#Real},*{#Real})
>  loop1 i m dir x1 y1 x2 y2
>  | i == m = (x2,y2)
>  #! x2 = {x2 & [i]=0.0}
>  #! y2 = {y2 & [i]=0.0}
>  #! arg = (~(toReal dir))*2.0*3.141592654*(toReal i)/(toReal m)
>  # (x2,y2) = loop2 i 0 m arg x1 y1 x2 y2
>  = loop1 (i+1) m dir x1 y1 x2 y2
>  
>  loop2 :: Int Int !Int !Real *{#Real} *{#Real} *{#Real} *{#Real} -> 
> (*{#Real},*{#Real})
>  loop2 i k m arg x1 y1 x2 y2
>  | k == m = (x2,y2)
>  #! cosarg = cos ((toReal k)*arg)
>  #! sinarg = sin ((toReal k)*arg)
>  #! auxx = x2.[i]
>  #! auxy = y2.[i]
>  #! vx = x1.[k]
>  #! vy = y1.[k]
>  = loop2 i (k+1) m arg x1 y1 {x2 & [i]=(auxx + (vx*cosarg - 
> vy*sinarg))} {y2 & [i]=(auxy + (vx*sinarg + vy*cosarg))}
> Thanks in advance,