diff options
Diffstat (limited to 'src/algebra/perman.spad.pamphlet')
| -rw-r--r-- | src/algebra/perman.spad.pamphlet | 11 |
1 files changed, 6 insertions, 5 deletions
diff --git a/src/algebra/perman.spad.pamphlet b/src/algebra/perman.spad.pamphlet index 49519edb..b45620a4 100644 --- a/src/algebra/perman.spad.pamphlet +++ b/src/algebra/perman.spad.pamphlet @@ -152,7 +152,6 @@ Permanent(n : PositiveInteger, R : Ring with commutative("*")): x : SM a,b : R - i,j,k,l : I permanent3(x) == -- This algorithm is based upon the principle of inclusion- @@ -214,8 +213,9 @@ Permanent(n : PositiveInteger, R : Ring with commutative("*")): while j ~= n repeat -- we sum over all subsets of (1,...,n-1) sgn := -sgn b := sgn - if vv.1.j = 1 then k := -1 - else k := 1 -- was that element deleted(k=-1) or added(k=1)? + k := + vv.1.j = 1 => -1 + 1 -- was that element deleted(k=-1) or added(k=1)? for i in 1..n repeat w.i := w.i +$R k *$R x(i,j) b := b *$R w.i @@ -259,8 +259,9 @@ Permanent(n : PositiveInteger, R : Ring with commutative("*")): while j ~= n repeat -- we sum over all subsets of (1,...,n-1) sgn := -sgn b := sgn - if vv.1.j = 1 then k := -1 - else k := 1 -- was that element deleted(k=-1) or added(k=1)? + k := + vv.1.j = 1 => -1 + 1 -- was that element deleted(k=-1) or added(k=1)? c := k * two for i in 1..n repeat w.i := w.i +$R c *$R x(i,j) |