abs min feature implementation

DIRECTORY.md

@@ -80,6 +80,7 @@
 
 ## Maths
   * [Abs Max](https://github.com/TheAlgorithms/Ruby/blob/master/maths/abs_max.rb)
+  * [Abs Min](https://github.com/TheAlgorithms/Ruby/blob/master/maths/abs_min.rb)
   * [Abs](https://github.com/TheAlgorithms/Ruby/blob/master/maths/abs.rb)
   * [Abs Test](https://github.com/TheAlgorithms/Ruby/blob/master/maths/abs_test.rb)
   * [Add](https://github.com/TheAlgorithms/Ruby/blob/master/maths/add.rb)

maths/abs_min.rb

@@ -0,0 +1,34 @@
+# A ruby program to find absolute minimum
+# Mathematical representation of abs min = ((a + b - absoulte(a - b)) / 2)
+
+def abs_min(x, y)
+  num = x - y
+  min_value = ((x + y - num.abs()) / 2)
+  "The Abs Min of #{x} and #{y} is #{min_value}."
+  rescue
+    "Error: Provide number only!"
+end
+
+#
+# Valid inputs
+#
+puts abs_min(10, 20)
+# The Abs Min of 10 and 20 is 10.
+
+puts abs_min(-10, -1)
+# The Abs Min of -10 and -1 is -10.
+
+puts abs_min(9, -121)
+# The Abs Min of 9 and -121 is -121.
+
+#
+# Invalid inputs
+#
+puts abs_min(2, "-1")
+# Error: Provide number only!
+
+puts abs_min("3", "5")
+# Error: Provide number only!
+
+puts abs_min("a", "5")
+# Error: Provide number only!