Changeset bf75121 in git for Singular/LIB/gradedModules.lib

Timestamp:

Apr 29, 2015, 6:38:52 PM (9 years ago)

Author:

Oleksandr Motsak <motsak@…>

Branches:

(u'spielwiese', 'd1b01e9d51ade4b46b745d3bada5c5f3696be3a8')

Children:

abc5f14430fc46985a74afdd4a426157fa69263e

Parents:

e5e219020eee81e7dc5562da6a0aa0a4a1e2b3e3

Message:

Changes in documentation and in grtwists

File:

• Singular/LIB/gradedModules.lib (modified) (5 diffs)

Singular/LIB/gradedModules.lib

@@ -26 +26 @@
     grdeg(M)        compute graded degrees of columns of the map M
     grview(M)       view the graded structure of map M
-    grshift(M,d)    shift graded module coker(M) by d
+    grshift(M,d)    shift graded module coker(M) by +d
     grzero()        presentation of S(0)^1
-    grtwist(r,d)    presentation of S(-d)^r
-    grtwists(v)     presentation of S(-v[1])+...+S(-v[size(v)])
+    grtwist(r,d)    presentation of S(d)^r
+    grtwists(v)     presentation of S(v[1])+...+S(v[size(v)])
     grsum(M,N)      direct sum of two graded modules coker(M) + coker(N)
     grpower(M,p)    direct p-th power of graded module coker(M)
@@ -865 +865 @@
 "USAGE:  grshift(A, d), graded objects A, int d
 RETURN:  shifted graded object
-PURPOSE: shift the grading on A by d: A_i -> A_{i+/-d}?
+PURPOSE: shift the grading on A by d: A(i) -> A(i+d)
 EXAMPLE: example grshift; shows an example
 "
@@ -1140 +1140 @@
   int l = size(v);
   module Z; Z[l] = [0];
-  Z = grobj(Z, v, v); // will set the rank as well
+  Z = grobj(Z, -v, -v); // will set the rank as well
   return(Z);
 }
@@ -1170 +1170 @@
 
   // zero syzygy?
-  return( grtwists(v) ); // ???
+  return( grtwists(-v) ); // ???
 }
 example
@@ -1249 +1249 @@
   for ( i = 1; i <= l; i++ )
   {
-    if( size(r[i]) == 0 ){ r[i] = grtwists(v); i++; break;   }
+    if( size(r[i]) == 0 ){ r[i] = grtwists(-v); i++; break;   }
 
     r[i] = grobj(r[i], v); v = grdeg(r[i]);