* algebra/matcat.spad.pamphlet (MatrixCategory) [matrix]:

	Add overload that takes sizes and function to compute entries.

1 files changed, 12 insertions, 0 deletions

diff --git a/src/algebra/matcat.spad.pamphlet b/src/algebra/matcat.spad.pamphlet
index d84feb2b..d0bcd007 100644
--- a/src/algebra/matcat.spad.pamphlet
+++ b/src/algebra/matcat.spad.pamphlet
@@ -37,6 +37,8 @@ MatrixCategory(R,Row,Col): Category == Definition where
   R   : Ring
   Row : FiniteLinearAggregate R
   Col : FiniteLinearAggregate R
+  macro NNI == NonNegativeInteger
+  macro I == Integer
 
   Definition ==> TwoDimensionalArrayCategory(R,Row,Col) with
      shallowlyMutable
@@ -70,6 +72,9 @@ MatrixCategory(R,Row,Col): Category == Definition where
      matrix: List List R -> %
        ++ \spad{matrix(l)} converts the list of lists l to a matrix, where the
        ++ list of lists is viewed as a list of the rows of the matrix.
+     matrix: (NNI, NNI, (I,I) -> R) -> %
+       ++ \spad{matrix(n,m,f)} construcys and \spad{n * m} matrix with
+       ++ the \spad{(i,j)} entry equal to \spad{f(i,j)}.
      scalarMatrix: (NonNegativeInteger,R) -> %
        ++ \spad{scalarMatrix(n,r)} returns an n-by-n matrix with r's on the
        ++ diagonal and zeroes elsewhere.
@@ -264,6 +269,13 @@ MatrixCategory(R,Row,Col): Category == Definition where
            qsetelt!(ans,i,j,r)
        ans
 
+     matrix(n,m,f) ==
+       mat := new(n,m,0)
+       for i in minr mat..maxr mat repeat
+         for j in minc mat..maxc mat repeat
+           qsetelt!(mat,i,j,f(i,j))
+       mat
+
      scalarMatrix(n,r) ==
        ans := zero(n,n)
        for i in minr(ans)..maxr(ans) for j in minc(ans)..maxc(ans) repeat