From c89b0054ab1cd2401da4f35a2cbfbeae142dae10 Mon Sep 17 00:00:00 2001
From: Gerd Heber <gheber@hdfgroup.org>
Date: Mon, 3 Aug 2015 17:40:37 -0500
Subject: [PATCH] Added the SHOW-STRUCTURE function for simplicial sets from
 the Handbook p. 143.

---
 package.lisp             |  1 +
 src/simplicial-sets.lisp | 22 ++++++++++++++++++++++
 2 files changed, 23 insertions(+)

diff --git a/package.lisp b/package.lisp
index f9e56a4..9ea85c1 100644
--- a/package.lisp
+++ b/package.lisp
@@ -479,6 +479,7 @@
 	   NDGNR
 	   NFACE
 	   REMOVE-BIT
+	   SHOW-STRUCTURE
 	   SMST
 
 	   ;; smith.lisp
diff --git a/src/simplicial-sets.lisp b/src/simplicial-sets.lisp
index b7c3a74..a1b2cd3 100644
--- a/src/simplicial-sets.lisp
+++ b/src/simplicial-sets.lisp
@@ -490,3 +490,25 @@
 	(declare (type gmsm gmsm))
 	(unless (check-faces cmpr face dmns gmsm)
 	  (setf rslt nil))))))
+
+
+(DEFUN SHOW-STRUCTURE (smst dmns)
+  (declare
+   (type simplicial-set smst)
+   (fixnum dmns))
+  "--------------------------------------------------------------[function-doc]
+SHOW-STRUCTURE
+Args: (smst dmns)
+Shows the structure of the simplicial set SMST (i.e., generators and faces)
+from dimension 0 up to and including dimension DMNS.
+------------------------------------------------------------------------------"
+  (when (<= 0 dmns)
+    (dotimes (i (1+ dmns))
+      (format t "~2%Dimension = ~D:" i)
+      (case i
+	(0 (format t "~2%~8TVertices : ~8T~A" (basis smst 0)))
+	(otherwise
+	 (dolist (s (basis smst i))
+	   (format t "~2%~8TSimplex : ~A~2%~16TFaces : ~A"
+		   s (mapcar #'(lambda (j) (face smst j i s))
+			     (<a-b> 0 i)))))))))