3 files changed, 166 insertions, 6 deletions

diff --git a/apl9.h b/apl9.h
index 7c44980..63b6d7a 100644
--- a/apl9.h
+++ b/apl9.h
@@ -116,6 +116,8 @@ Array *mkscalarint(vlong);
 Array *duparray(Array *);
 int simplearray(Array *);
 int simplescalar(Array *);
+Array *extend(Array *, Array *);
+int scalarextend(Array *, Array *, Array **, Array **);
 
 /* eval.c */
 Datum *eval(Statement *);
@@ -141,6 +143,12 @@ Array *fnRavel(Array *);
 Array *fnShape(Array *);
 
 /* Dyadic functions from functions.h */
+Array *fnPlus(Array *, Array *);
+Array *fnMinus(Array *, Array *);
+Array *fnTimes(Array *, Array *);
+Array *fnDivide(Array *, Array *);
+Array *fnPower(Array *, Array *);
+Array *fnLogarithm(Array *, Array *);
 Array *fnLeft(Array *, Array *);
 Array *fnRight(Array *, Array *);
 Array *fnCatenateFirst(Array *, Array *);
diff --git a/array.c b/array.c
index 4913112..a2afc44 100644
--- a/array.c
+++ b/array.c
@@ -41,3 +41,41 @@ simplescalar(Array *a)
 {
 	return simplearray(a) && a->rank == 0;
 }
+
+Array *
+extend(Array *a, Array *b)
+{
+	/* extend the singleton a to the shape of b */
+	Array *shape = fnShape(b);
+	Array *res = fnReshape(shape, a);
+	freearray(shape);
+	return res;
+}
+
+int
+scalarextend(Array *a, Array *b, Array **aa, Array **bb)
+{
+	/* Extend the arrays a and b to have the same shape.
+	   The resulting arrays are stored in aa and bb,
+	   except when the ranks don't match or extension can't
+	   happen, in which case the function returns 0 and
+	   aa and bb are unchanged.
+	*/
+
+	if(a->size == 1 && b->size != 1){
+		*aa = extend(a, b);
+		*bb = fnSame(b);
+	}else if(b->size == 1 && a->size != 1){
+		*aa = fnSame(a);
+		*bb = extend(b, a);
+	}else if(a->size == b->size && a->rank == b->rank){
+		/* Check that each dimension matches */
+		for(int i = 0; i < a->rank; i++)
+			if(a->shape[i] != b->shape[i])
+				return 0;
+		*aa = fnSame(a);
+		*bb = fnSame(b);
+	}else
+		return 0;
+	return 1;
+}
\ No newline at end of file
diff --git a/functions.c b/functions.c
index bbac1a9..db9fe01 100644
--- a/functions.c
+++ b/functions.c
@@ -62,12 +62,12 @@ fnmonad monadfunctiondefs[] = {
 };
 
 fndyad dyadfunctiondefs[] = {
-	0, /* + */
-	0, /* - */
-	0, /* × */
-	0, /* ÷ */
-	0, /* * */
-	0, /* ⍟ */
+	fnPlus, /* + */
+	fnMinus, /* - */
+	fnTimes, /* × */
+	fnDivide, /* ÷ */
+	fnPower, /* * */
+	fnLogarithm, /* ⍟ */
 	0, /* ⌹ */
 	0, /* ○ */
 	0, /* ! */
@@ -189,6 +189,120 @@ fnShape(Array *right)
 /* Dyadic functions */
 
 Array *
+fnPlus(Array *left, Array *right)
+{
+	Array *leftarr;
+	Array *rightarr;
+	int rankok = scalarextend(left, right, &leftarr, &rightarr);
+	if(!rankok){
+		print("Ranks don't match lol\n");
+		exits(nil);
+	}
+
+	Array *res = duparray(leftarr);
+	for(int i = 0; i < leftarr->size; i++)
+		res->intdata[i] += rightarr->intdata[i];
+	freearray(leftarr);
+	freearray(rightarr);
+	return res;
+}
+
+Array *
+fnMinus(Array *left, Array *right)
+{
+	Array *leftarr;
+	Array *rightarr;
+	int rankok = scalarextend(left, right, &leftarr, &rightarr);
+	if(!rankok){
+		print("Ranks don't match lol\n");
+		exits(nil);
+	}
+
+	Array *res = duparray(leftarr);
+	for(int i = 0; i < leftarr->size; i++)
+		res->intdata[i] -= rightarr->intdata[i];
+	freearray(leftarr);
+	freearray(rightarr);
+	return res;
+}
+
+Array *
+fnTimes(Array *left, Array *right)
+{
+	Array *leftarr;
+	Array *rightarr;
+	int rankok = scalarextend(left, right, &leftarr, &rightarr);
+	if(!rankok){
+		print("Ranks don't match lol\n");
+		exits(nil);
+	}
+
+	Array *res = duparray(leftarr);
+	for(int i = 0; i < leftarr->size; i++)
+		res->intdata[i] *= rightarr->intdata[i];
+	freearray(leftarr);
+	freearray(rightarr);
+	return res;
+}
+
+Array *
+fnDivide(Array *left, Array *right)
+{
+	Array *leftarr;
+	Array *rightarr;
+	int rankok = scalarextend(left, right, &leftarr, &rightarr);
+	if(!rankok){
+		print("Ranks don't match lol\n");
+		exits(nil);
+	}
+
+	Array *res = duparray(leftarr);
+	for(int i = 0; i < leftarr->size; i++)
+		res->intdata[i] /= rightarr->intdata[i];
+	freearray(leftarr);
+	freearray(rightarr);
+	return res;
+}
+
+Array *
+fnPower(Array *left, Array *right)
+{
+	Array *leftarr;
+	Array *rightarr;
+	int rankok = scalarextend(left, right, &leftarr, &rightarr);
+	if(!rankok){
+		print("Ranks don't match lol\n");
+		exits(nil);
+	}
+
+	Array *res = duparray(leftarr);
+	for(int i = 0; i < leftarr->size; i++)
+		res->intdata[i] = pow(res->intdata[i], rightarr->intdata[i]);
+	freearray(leftarr);
+	freearray(rightarr);
+	return res;
+}
+
+Array *
+fnLogarithm(Array *left, Array *right)
+{
+	Array *leftarr;
+	Array *rightarr;
+	int rankok = scalarextend(left, right, &leftarr, &rightarr);
+	if(!rankok){
+		print("Ranks don't match lol\n");
+		exits(nil);
+	}
+
+	Array *res = duparray(leftarr);
+	for(int i = 0; i < leftarr->size; i++)
+		res->intdata[i] = log(rightarr->intdata[i])/log(res->intdata[i]);
+	freearray(leftarr);
+	freearray(rightarr);
+	return res;
+}
+
+Array *
 fnLeft(Array *left, Array *right)
 {
 	USED(right);