Knuth's power tree: Difference between revisions

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@@ Line 981: / Line 981: @@
         for i=1 to length(lvl) do
             integer x = lvl[i]
-            sequence py = path(x)
+            sequence px = path(x)
-            for j=1 to length(py) do
+            for j=1 to length(px) do
-                integer y = x+py[j]
+                integer y = x+px[j]
                 if getd_index(y,p)!=NULL then exit end if
                 setd(y,x,p)
@@ Line 996: / Line 996: @@
 include bigatom.e
-function treepow(object x, integer n)
+function treepow(object x, integer n, sequence pn = {})
 -- x can be atom or bigatom
 -- (asides: sequence r uses out-by-1 indexing, ie r[1] is for 0.
 --          pipa/pa/res perform useful type-checking, ie prevent
 --          this from trying to use something not yet calculated.)
-    sequence pn = path(n)
+    if pn={} then pn=path(n) end if
     sequence r = {BA_ONE,ba_new(x)}&repeat(0,max(0,n-1))
     integer p = 0
@@ Line 1,016: / Line 1,016: @@
 procedure showpow(atom x, integer n)
-    printf(1,"%48s : %3g ^ %d = %s\n", {sprint(path(n)),x,n,treepow(x,n)})
+    sequence pn = path(n)
+    printf(1,"%48s : %3g ^ %d = %s\n", {sprint(pn),x,n,treepow(x,n,pn)})
 end procedure