new file mode 100644
--- /dev/null
+++ b/test/gsp600.ijs
@@ -0,0 +1,139 @@
+NB. " monad -------------------------------------------------------------
+
+d=: (13 5 7?@$2)*13 5 7?@$5
+c=: ; (i.1+r) <"1@comb&.>r=:#$d
+
+double=: 3 : '+.y'
+
+f=: 3 : 0
+ b=. (double"0 d) -: t=. double"0 s=:(2;y)$.d
+ if. b *. 0<#$t do. *./ scheck t else. b end.
+)
+
+f&>c
+
+A=: 1 : 0
+  :
+ b=. (u"x d) -: t=. u"x s=:(2;y)$.d
+ if. b *. 0<#$t do. *./ scheck t else. b end.
+)
+
+c=: ; (i.1+r) <"1@comb&.>r=:#$d
+
+ravel=: 3 : ', y'
+sum  =: 3 : '+/y'
+rev  =: 3 : '|.y'
+mean =: +/ % #
+
+(i.>:r) ]     A&>/ c
+(i.>:r) sum   A&>/ c
+(i.>:r) ravel A&>/ c
+(i.>:r) rev   A&>/ c
+(i.>:r) #     A&>/ c
+(i.>:r) mean  A&>/ c
+
+d=: 2 3 4$0
+c=: ; (i.1+r) <"1@comb&.>r=:#$d
+(i.>:r) mean  A&>/c
+
+($"2 x) -: $"2 $. x=:2 3 3$12
+
+(<1 0) 10 11&(4 : 'x o. y') A&>/c
+
+'non-unique sparse elements' -: $"2 etx $. 2 3 4$12
+
+
+NB. " dyad --------------------------------------------------------------
+
+A2=: 1 : 0
+  :
+ xx=: (2;x)$.x0
+ yy=: (2;y)$.y0
+ b=. (x0 u"r y0) -: t=: xx u"r yy
+ if. b *. 0<#$t do.*./ scheck t else. b end.
+)
+
+minus=: 4 : 'x -  y'
+cat  =: 4 : 'x ,  y'
+rot  =: 4 : 'x |. y'
+
+x0=: (13 5?@$2)*13 5 7?@$500
+y0=: (13 5?@$2)*13 5 7?@$500
+c=: ; (i.1+r) <"1@comb&.>r=:#$x0
+
+minus A2&>/~c [ r=: 0
+minus A2&>/~c [ r=: 1
+minus A2&>/~c [ r=: 2
+minus A2&>/~c [ r=: 3
+
+cat   A2&>/~c [ r=: 0
+cat   A2&>/~c [ r=: 1
+cat   A2&>/~c [ r=: 2
+cat   A2&>/~c [ r=: 3
+
+x0=: (13 5 7?@$2)*13 5 7?@$5
+y0=:              13 5 7  $0
+c=: ; (i.1+r) <"1@comb&.>r=:#$x0
+
+minus A2&>/~c [ r=: 0
+minus A2&>/~c [ r=: 1
+minus A2&>/~c [ r=: 2
+minus A2&>/~c [ r=: 3
+
+cat   A2&>/~c [ r=: 0
+cat   A2&>/~c [ r=: 1
+cat   A2&>/~c [ r=: 2
+cat   A2&>/~c [ r=: 3
+
+x0=:              13 5 7  $0
+y0=: (13 5 7?@$2)*13 5 7?@$5
+c=: ; (i.1+r) <"1@comb&.>r=:#$x0
+
+minus A2&>/~c [ r=: 0
+minus A2&>/~c [ r=: 1
+minus A2&>/~c [ r=: 2
+minus A2&>/~c [ r=: 3
+
+cat   A2&>/~c [ r=: 0
+cat   A2&>/~c [ r=: 1
+cat   A2&>/~c [ r=: 2
+cat   A2&>/~c [ r=: 3
+
+x0=: 13 5 7$0
+y0=: 13 5 7$0
+c=: ; (i.1+r) <"1@comb&.>r=:#$x0
+
+minus A2&>/~c [ r=: 0
+minus A2&>/~c [ r=: 1
+minus A2&>/~c [ r=: 2
+minus A2&>/~c [ r=: 3
+
+cat   A2&>/~c [ r=: 0
+cat   A2&>/~c [ r=: 1
+cat   A2&>/~c [ r=: 2
+cat   A2&>/~c [ r=: 3
+
+x0=: (13 5  ?@$2)*13 5  ?@$5
+y0=: (13 5 7?@$2)*13 5 7?@$5
+c=: ; (i.1+r) <"1@comb&.>r=:#$x0
+d=: ; (i.1+r) <"1@comb&.>r=:#$y0
+c rot A2&>/ d [ r=: 0 1
+
+x0=: (13  ?@$2)*13 2   ?@$5
+y0=: (13 7?@$2)*13 7 17?@$5
+c=: ; (i.1+r) <"1@comb&.>r=:#$x0
+d=: ; (i.1+r) <"1@comb&.>r=:#$y0
+c rot A2&>/ d [ r=: 1 2
+
+f=: 3 : 0
+ (10 11 o."1 0 xx) -: 10 11 o."1 0 s=: (2;y)$.xx
+)
+
+xx=: (13 7?@$2)*13 7 4 2?@$5
+c=: ; (i.1+r) <"1@comb&.>r=:#$xx
+f&>c
+
+
+4!:55 ;:'A A2 c cat d double f mean minus q r ravel rev rot s sum t x x0 xx y y0 yy'
+
+