--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/diags.m	Wed Feb 08 09:18:08 2017 +0100
@@ -0,0 +1,9 @@
+function A = diags(B,d,m,n)
+    assert(size(B,1) == m);
+
+    A = repmat(B(:,1)*0, [1, n]);
+
+    for i = 1:size(B,2)
+        A(:,d(i)+ (1:m)) = A(:,d(i)+ (1:m)) + diag(B(:,i));
+    end
+end