add matrix and statistics utilities

Author: jbytecode

src/main/scala/matrix.scala

@@ -86,6 +86,11 @@ object Matrix:
 
   def applyFunctionToColumns(a: Mat, f: Vec => Double): Vec = a.transpose.map(f)
 
+  def applyFunctionsToColumns(a: Mat, f: Array[Vec => Double]): Vec = 
+    a.transpose
+      .zip(f)
+      .map((col, func) => func(col))
+
   def applyFunctionToRows(a: Mat, f: Vec => Double): Vec = a.map(f)
 
   def multiplyRowByScalar(a: Mat, i: Int, scalar: Double): Mat =

src/main/scala/statistics.scala

@@ -4,6 +4,10 @@ import scala.math.{log, exp}
 
 object Statistics:
 
+  def maximum(a: Vec): Double = a.max
+
+  def minimum(a: Vec): Double = a.min
+
   def mean(a: Vec): Double = a.sum / a.length
 
   def variance(a: Vec): Double =