From 40ffa8d6fc5380a4f2911178f48ab07c4084997f Mon Sep 17 00:00:00 2001
From: Igor Dunaev <idunaev71@gmail.com>
Date: Sun, 28 Apr 2024 18:36:54 +0300
Subject: [PATCH] Remove unnecessary code from outer sift() function

---
 .../kmath/series/EmpiricalModeDecomposition.kt   | 16 ++++------------
 1 file changed, 4 insertions(+), 12 deletions(-)

diff --git a/kmath-stat/src/commonMain/kotlin/space/kscience/kmath/series/EmpiricalModeDecomposition.kt b/kmath-stat/src/commonMain/kotlin/space/kscience/kmath/series/EmpiricalModeDecomposition.kt
index d1f4f43d2..467ea3201 100644
--- a/kmath-stat/src/commonMain/kotlin/space/kscience/kmath/series/EmpiricalModeDecomposition.kt
+++ b/kmath-stat/src/commonMain/kotlin/space/kscience/kmath/series/EmpiricalModeDecomposition.kt
@@ -76,17 +76,7 @@ public class EmpiricalModeDecomposition<BA, L: Number> (
      * @return [SiftingResult.NotEnoughExtrema] is returned if the signal has too few extrema to extract a mode.
      * Success of an appropriate type (See [SiftingResult.Success] class) is returned otherwise.
      */
-    private fun sift(signal: Series<Double>): SiftingResult = (seriesAlgebra) {
-        val mean = findMean(signal) ?: return SiftingResult.NotEnoughExtrema
-        val protoMode = signal.zip(mean) { s, m -> s - m }
-        val sNumber = if (protoMode.sCondition()) 1 else 0
-        return when {
-            maxSiftIterations == 1 -> SiftingResult.MaxIterationsReached(protoMode)
-            sNumber >= sConditionThreshold -> SiftingResult.SNumberReached(protoMode)
-            relativeDifference(protoMode, signal) < siftingDelta * signal.size -> SiftingResult.DeltaReached(protoMode)
-            else -> siftInner(protoMode, 2, sNumber)
-        }
-    }
+    private fun sift(signal: Series<Double>): SiftingResult = siftInner(signal, 1, 0)
 
     /**
      * Compute a single iteration of the sifting process.
@@ -96,7 +86,9 @@ public class EmpiricalModeDecomposition<BA, L: Number> (
         iterationNumber: Int,
         sNumber: Int
     ): SiftingResult = (seriesAlgebra) {
-        val mean = findMean(prevMode) ?: return SiftingResult.SignalFlattened(prevMode)
+        val mean = findMean(prevMode) ?:
+            return if (iterationNumber == 1) SiftingResult.NotEnoughExtrema
+            else SiftingResult.SignalFlattened(prevMode)
         val mode = prevMode.zip(mean) { p, m -> p - m }
         val newSNumber = if (mode.sCondition()) sNumber + 1 else sNumber
         return when {