From a334aaae7869c955659e46c75a301b336d6d8011 Mon Sep 17 00:00:00 2001
From: Andrew Heather <aht@esi-group.com>
Date: Mon, 15 Feb 2021 12:51:35 +0000
Subject: [PATCH] ENH: noiseModel gainX - protect against very small input
 frequencies

---
 .../noise/noiseModels/noiseModel/noiseModel.C | 20 +++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/src/randomProcesses/noise/noiseModels/noiseModel/noiseModel.C b/src/randomProcesses/noise/noiseModels/noiseModel/noiseModel.C
index 82cd1e9c4f..efc36e3346 100644
--- a/src/randomProcesses/noise/noiseModels/noiseModel/noiseModel.C
+++ b/src/randomProcesses/noise/noiseModels/noiseModel/noiseModel.C
@@ -434,6 +434,11 @@ Foam::scalar Foam::noiseModel::RAf(const scalar f) const
 
 Foam::scalar Foam::noiseModel::gainA(const scalar f) const
 {
+    if (f < SMALL)
+    {
+        return 0;
+    }
+
     return 20*log10(RAf(f)) - 20*log10(RAf(1000));
 }
 
@@ -456,6 +461,11 @@ Foam::scalar Foam::noiseModel::RBf(const scalar f) const
 
 Foam::scalar Foam::noiseModel::gainB(const scalar f) const
 {
+    if (f < SMALL)
+    {
+        return 0;
+    }
+
     return 20*log10(RBf(f)) - 20*log10(RBf(1000));
 }
 
@@ -473,6 +483,11 @@ Foam::scalar Foam::noiseModel::RCf(const scalar f) const
 
 Foam::scalar Foam::noiseModel::gainC(const scalar f) const
 {
+    if (f < SMALL)
+    {
+        return 0;
+    }
+
     return 20*log10(RCf(f)) - 20*log10(RCf(1000));
 }
 
@@ -492,6 +507,11 @@ Foam::scalar Foam::noiseModel::RDf(const scalar f) const
 
 Foam::scalar Foam::noiseModel::gainD(const scalar f) const
 {
+    if (f < SMALL)
+    {
+        return 0;
+    }
+
     return 20*log10(RDf(f));
 }