Ethiopian multiplication: Difference between revisions

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 *[http://www.ncetm.org.uk/blogs/3064 Ethiopian multiplication]
 *[http://www.bbc.co.uk/dna/h2g2/A22808126 Russian Peasant Multiplication]
+=={{header|AutoHotkey}}==
+<lang AutoHotkey>MsgBox % Ethiopian(17, 34) "`n" Ethiopian2(17, 34)
+; func definitions:
+half( x ) {
+	return x >> 1
+}
+double( x ) {
+	return x << 1
+}
+isEven( x ) {
+	return x & 1 == 0
+}
+Ethiopian( a, b ) {
+	r := (isEven(a) ? 0 : b)
+	Loop
+	{
+		a := half(a)
+		b := double(b)
+		if !isEven(a)
+			r += b
+		if (a = 1)
+			break
+	}
+	return r
+}
+; or a recursive function:
+Ethiopian2( a, b, r = 0 ) { ;omit r param on initial call
+	return a==1 ? r+b : Ethiopian2( half(a), double(b), !isEven(a) ? r+b : r )
+}</lang>
 =={{header|AWK}}==