September 2017 Update

Task/Matrix-arithmetic/Jq/matrix-arithmetic-4.jq

@@ -0,0 +1,8 @@
+# Requires lup/0
+def det:
+  def product_diagonal:
+    . as $m | reduce range(0;length) as $i (1; . * $m[$i][$i]);
+  def tidy: if . == -0 then 0 else . end;
+  lup
+  | (.[0]|product_diagonal) as $l
+  | if $l == 0 then 0 else $l * (.[1]|product_diagonal) | tidy end ;