adding "shape" function, plus tests

run-tests.coffee

@@ -96,6 +96,7 @@ selftest  = ->
 	test_simplify()
 	test_roots()
 	test_eigen()
+	test_shape()
 	mini_test()
 
 

runtime/defs.coffee

@@ -175,6 +175,7 @@ SGN = counter++
 SIMPLIFY = counter++
 SIN = counter++
 SINH = counter++
+SHAPE = counter++
 SQRT = counter++
 STOP = counter++
 SUBST = counter++

runtime/init.coffee

@@ -138,6 +138,7 @@ init = ->
 	std_symbol("simplify", SIMPLIFY)
 	std_symbol("sin", SIN)
 	std_symbol("sinh", SINH)
+	std_symbol("shape", SHAPE)
 	std_symbol("sqrt", SQRT)
 	std_symbol("stop", STOP)
 	std_symbol("subst", SUBST)

sources/eval.coffee

@@ -157,6 +157,7 @@ Eval_cons = ->
 		when SIMPLIFY then Eval_simplify()
 		when SIN then Eval_sin()
 		when SINH then Eval_sinh()
+		when SHAPE then Eval_shape()
 		when SQRT then Eval_sqrt()
 		when STOP then Eval_stop()
 		when SUBST then Eval_subst()

sources/shape.coffee

@@ -0,0 +1,50 @@
+# shape of tensor
+
+
+
+Eval_shape = ->
+	push(cadr(p1))
+	Eval()
+	shape()
+
+shape = ->
+	i = 0
+	ndim = 0
+	t = 0
+	ai = []
+	an = []
+	for i in [0...MAXDIM]
+		ai[i] = 0
+		an[i] = 0
+
+	#U **a, **b
+
+	save()
+
+	p1 = pop()
+
+	if (!istensor(p1))
+		if (!iszero(p1))
+			stop("transpose: tensor expected, 1st arg is not a tensor")
+		push(zero)
+		restore()
+		return
+
+	ndim = p1.tensor.ndim
+
+
+	p2 = alloc_tensor(ndim)
+
+	p2.tensor.ndim = 1
+	p2.tensor.dim[0] = ndim
+
+
+
+	for i in [0...ndim]
+		push_integer(p1.tensor.dim[i])
+		p2.tensor.elem[i] = pop()
+
+	push(p2)
+
+	restore()
+

sources/transpose.coffee

@@ -48,7 +48,14 @@ transpose = ->
 	ndim = p1.tensor.ndim
 	nelem = p1.tensor.nelem
 
-	# vector?
+	# is it a vector?
+	# so here it's something curious - note how vectors are
+	# not really special two-dimensional matrices, but rather
+	# 1-dimension objects (like tensors can be). So since
+	# they have one dimension, transposition has no effect.
+	# (as opposed as if they were special two-dimensional
+	# matrices)
+	# see also Ran Pan, Tensor Transpose and Its Properties. CoRR abs/1411.1503 (2014)
 
 	if (ndim == 1)
 		push(p1)

tests/shape.coffee

@@ -0,0 +1,26 @@
+test_shape = ->
+	run_test [
+
+		# see transpose function source to see why
+		# transposition has no effect on vectors.
+
+		"shape((A,B,C))",
+		"(3)",
+
+		"shape(transpose((A,B,C)))",
+		"(3)",
+
+		"shape(((A),(B),(C)))",
+		"(3)",
+
+		"shape(transpose(((A),(B),(C))))",
+		"(3)",
+
+		"shape(((A,B),(C,D),(E,F)))",
+		"(3,2)",
+
+		"shape(transpose(((A,B),(C,D),(E,F))))",
+		"(2,3)",
+
+	]
+