diff --git a/orx-gradient-descent/src/main/kotlin/GradientDescent.kt b/orx-gradient-descent/src/main/kotlin/GradientDescent.kt
index a1b325be..f4bbf713 100644
--- a/orx-gradient-descent/src/main/kotlin/GradientDescent.kt
+++ b/orx-gradient-descent/src/main/kotlin/GradientDescent.kt
@@ -89,9 +89,9 @@ private fun norm2(x: DoubleArray): Double {
     return sqrt(x.sumByDouble { it * it })
 }
 
-fun dot(x: DoubleArray, y: DoubleArray): Double = (x.mapIndexed { index, it -> it * y[index] }).sum()
+private fun dot(x: DoubleArray, y: DoubleArray): Double = (x.mapIndexed { index, it -> it * y[index] }).sum()
 
-fun dot(x: Array<DoubleArray>, y: DoubleArray): DoubleArray = DoubleArray(x.size) { dot(x[it], y) }
+private fun dot(x: Array<DoubleArray>, y: DoubleArray): DoubleArray = DoubleArray(x.size) { dot(x[it], y) }
 
 class MinimizationResult(val solution: DoubleArray, val value: Double, val gradient: DoubleArray,
                          val inverseHessian: Array<DoubleArray>, val iterations: Int)