Use ratios of natural logs rather than to base ten

Natural log is marginally cheaper to compute and a ratio of logs, to a
given base, doesn't actually depend on the base; log(a)/log(b) is the
logarithm of a to base b.

Tidy up some duplication into a use of a ternary expression to
simplify one use of this, in the process.

Change-Id: Ic91dc0b4e9255f20f2f6e3d71c32a37f759d623d
Reviewed-by: Jarek Kobus <jaroslaw.kobus@qt.io>
Reviewed-by: Miikka Heikkinen <miikka.heikkinen@qt.io>

11 files changed, 63 insertions, 68 deletions

diff --git a/src/charts/axis/chartaxiselement.cpp b/src/charts/axis/chartaxiselement.cpp
index 1155257b..692400ea 100644
--- a/src/charts/axis/chartaxiselement.cpp
+++ b/src/charts/axis/chartaxiselement.cpp
@@ -555,12 +555,7 @@ QStringList ChartAxisElement::createLogValueLabels(qreal min, qreal max, qreal b
     if (max <= min || ticks < 1)
         return labels;
 
-    int firstTick;
-    if (base > 1)
-        firstTick = qCeil(std::log10(min) / std::log10(base));
-    else
-        firstTick = qCeil(std::log10(max) / std::log10(base));
-
+    const int firstTick = qCeil(qLn(base > 1 ? min : max) / qLn(base));
     if (format.isEmpty()) {
         int n = 0;
         if (ticks > 1)
diff --git a/src/charts/axis/logvalueaxis/chartlogvalueaxisx.cpp b/src/charts/axis/logvalueaxis/chartlogvalueaxisx.cpp
index f20c9942..43abf724 100644
--- a/src/charts/axis/logvalueaxis/chartlogvalueaxisx.cpp
+++ b/src/charts/axis/logvalueaxis/chartlogvalueaxisx.cpp
@@ -53,8 +53,8 @@ QList<qreal> ChartLogValueAxisX::calculateLayout() const
     QList<qreal> points;
     points.resize(m_axis->tickCount());
 
-    const qreal logMax = std::log10(m_axis->max()) / std::log10(m_axis->base());
-    const qreal logMin = std::log10(m_axis->min()) / std::log10(m_axis->base());
+    const qreal logMax = qLn(m_axis->max()) / qLn(m_axis->base());
+    const qreal logMin = qLn(m_axis->min()) / qLn(m_axis->base());
     const qreal leftEdge = qMin(logMin, logMax);
     const qreal ceilEdge = std::ceil(leftEdge);
 
diff --git a/src/charts/axis/logvalueaxis/chartlogvalueaxisy.cpp b/src/charts/axis/logvalueaxis/chartlogvalueaxisy.cpp
index 6f7b92af..8c65aa54 100644
--- a/src/charts/axis/logvalueaxis/chartlogvalueaxisy.cpp
+++ b/src/charts/axis/logvalueaxis/chartlogvalueaxisy.cpp
@@ -53,8 +53,8 @@ QList<qreal> ChartLogValueAxisY::calculateLayout() const
     QList<qreal> points;
     points.resize(m_axis->tickCount());
 
-    const qreal logMax = std::log10(m_axis->max()) / std::log10(m_axis->base());
-    const qreal logMin = std::log10(m_axis->min()) / std::log10(m_axis->base());
+    const qreal logMax = qLn(m_axis->max()) / qLn(m_axis->base());
+    const qreal logMin = qLn(m_axis->min()) / qLn(m_axis->base());
     const qreal leftEdge = qMin(logMin, logMax);
     const qreal ceilEdge = std::ceil(leftEdge);
 
diff --git a/src/charts/axis/logvalueaxis/polarchartlogvalueaxisangular.cpp b/src/charts/axis/logvalueaxis/polarchartlogvalueaxisangular.cpp
index ad864796..aed8d9fc 100644
--- a/src/charts/axis/logvalueaxis/polarchartlogvalueaxisangular.cpp
+++ b/src/charts/axis/logvalueaxis/polarchartlogvalueaxisangular.cpp
@@ -1,6 +1,6 @@
 /****************************************************************************
 **
-** Copyright (C) 2016 The Qt Company Ltd.
+** Copyright (C) 2021 The Qt Company Ltd.
 ** Contact: https://www.qt.io/licensing/
 **
 ** This file is part of the Qt Charts module of the Qt Toolkit.
@@ -55,8 +55,8 @@ QList<qreal> PolarChartLogValueAxisAngular::calculateLayout() const
     QList<qreal> points;
     points.resize(logValueAxis->tickCount());
 
-    const qreal logMax = std::log10(logValueAxis->max()) / std::log10(logValueAxis->base());
-    const qreal logMin = std::log10(logValueAxis->min()) / std::log10(logValueAxis->base());
+    const qreal logMax = qLn(logValueAxis->max()) / qLn(logValueAxis->base());
+    const qreal logMin = qLn(logValueAxis->min()) / qLn(logValueAxis->base());
     const qreal startEdge = qMin(logMin, logMax);
     const qreal delta = 360.0 / qAbs(logMax - logMin);
     const qreal initialSpan = (std::ceil(startEdge) - startEdge) * delta;
diff --git a/src/charts/axis/logvalueaxis/polarchartlogvalueaxisradial.cpp b/src/charts/axis/logvalueaxis/polarchartlogvalueaxisradial.cpp
index 122125c0..92d5664d 100644
--- a/src/charts/axis/logvalueaxis/polarchartlogvalueaxisradial.cpp
+++ b/src/charts/axis/logvalueaxis/polarchartlogvalueaxisradial.cpp
@@ -1,6 +1,6 @@
 /****************************************************************************
 **
-** Copyright (C) 2016 The Qt Company Ltd.
+** Copyright (C) 2021 The Qt Company Ltd.
 ** Contact: https://www.qt.io/licensing/
 **
 ** This file is part of the Qt Charts module of the Qt Toolkit.
@@ -54,8 +54,8 @@ QList<qreal> PolarChartLogValueAxisRadial::calculateLayout() const
     QList<qreal> points;
     points.resize(logValueAxis->tickCount());
 
-    const qreal logMax = std::log10(logValueAxis->max()) / std::log10(logValueAxis->base());
-    const qreal logMin = std::log10(logValueAxis->min()) / std::log10(logValueAxis->base());
+    const qreal logMax = qLn(logValueAxis->max()) / qLn(logValueAxis->base());
+    const qreal logMin = qLn(logValueAxis->min()) / qLn(logValueAxis->base());
     const qreal innerEdge = logMin < logMax ? logMin : logMax;
     const qreal delta = (axisGeometry().width() / 2.0) / qAbs(logMax - logMin);
     const qreal initialSpan = (std::ceil(innerEdge) - innerEdge) * delta;
diff --git a/src/charts/domain/logxlogydomain.cpp b/src/charts/domain/logxlogydomain.cpp
index 575de135..2660ea18 100644
--- a/src/charts/domain/logxlogydomain.cpp
+++ b/src/charts/domain/logxlogydomain.cpp
@@ -1,6 +1,6 @@
 /****************************************************************************
 **
-** Copyright (C) 2016 The Qt Company Ltd.
+** Copyright (C) 2021 The Qt Company Ltd.
 ** Contact: https://www.qt.io/licensing/
 **
 ** This file is part of the Qt Charts module of the Qt Toolkit.
@@ -62,8 +62,8 @@ void LogXLogYDomain::setRange(qreal minX, qreal maxX, qreal minY, qreal maxY)
         m_minX = minX;
         m_maxX = maxX;
         axisXChanged = true;
-        qreal logMinX = std::log10(m_minX) / std::log10(m_logBaseX);
-        qreal logMaxX = std::log10(m_maxX) / std::log10(m_logBaseX);
+        qreal logMinX = qLn(m_minX) / qLn(m_logBaseX);
+        qreal logMaxX = qLn(m_maxX) / qLn(m_logBaseX);
         m_logLeftX = logMinX < logMaxX ? logMinX : logMaxX;
         m_logRightX = logMinX > logMaxX ? logMinX : logMaxX;
         if(!m_signalsBlocked)
@@ -74,8 +74,8 @@ void LogXLogYDomain::setRange(qreal minX, qreal maxX, qreal minY, qreal maxY)
         m_minY = minY;
         m_maxY = maxY;
         axisYChanged = true;
-        qreal logMinY = std::log10(m_minY) / std::log10(m_logBaseY);
-        qreal logMaxY = std::log10(m_maxY) / std::log10(m_logBaseY);
+        qreal logMinY = qLn(m_minY) / qLn(m_logBaseY);
+        qreal logMaxY = qLn(m_maxY) / qLn(m_logBaseY);
         m_logLeftY = logMinY < logMaxY ? logMinY : logMaxY;
         m_logRightY = logMinY > logMaxY ? logMinY : logMaxY;
         if (!m_signalsBlocked)
@@ -166,18 +166,18 @@ QPointF LogXLogYDomain::calculateGeometryPoint(const QPointF &point, bool &ok) c
     qreal x(0);
     qreal y(0);
     if (point.x() > 0 && point.y() > 0) {
-        x = ((std::log10(point.x()) / std::log10(m_logBaseX)) - m_logLeftX) * deltaX;
-        y = ((std::log10(point.y()) / std::log10(m_logBaseY)) - m_logLeftY) * deltaY;
+        x = ((qLn(point.x()) / qLn(m_logBaseX)) - m_logLeftX) * deltaX;
+        y = ((qLn(point.y()) / qLn(m_logBaseY)) - m_logLeftY) * deltaY;
         ok = true;
     } else {
         qWarning() << "Logarithms of zero and negative values are undefined.";
         ok = false;
         if (point.x() > 0)
-            x = ((std::log10(point.x()) / std::log10(m_logBaseX)) - m_logLeftX) * deltaX;
+            x = ((qLn(point.x()) / qLn(m_logBaseX)) - m_logLeftX) * deltaX;
         else
             x = 0;
         if (point.y() > 0)
-            y = ((std::log10(point.y()) / std::log10(m_logBaseY)) - m_logLeftY) * deltaY;
+            y = ((qLn(point.y()) / qLn(m_logBaseY)) - m_logLeftY) * deltaY;
         else
             y = 0;
     }
@@ -198,10 +198,10 @@ QList<QPointF> LogXLogYDomain::calculateGeometryPoints(const QList<QPointF> &lis
 
     for (int i = 0; i < list.count(); ++i) {
         if (list[i].x() > 0 && list[i].y() > 0) {
-            qreal x = ((std::log10(list[i].x()) / std::log10(m_logBaseX)) - m_logLeftX) * deltaX;
+            qreal x = ((qLn(list[i].x()) / qLn(m_logBaseX)) - m_logLeftX) * deltaX;
             if (m_reverseX)
                 x = m_size.width() - x;
-            qreal y = ((std::log10(list[i].y()) / std::log10(m_logBaseY)) - m_logLeftY) * deltaY;
+            qreal y = ((qLn(list[i].y()) / qLn(m_logBaseY)) - m_logLeftY) * deltaY;
             if (!m_reverseY)
                 y = m_size.height() - y;
             result[i].setX(x);
@@ -260,8 +260,8 @@ bool LogXLogYDomain::detachAxis(QAbstractAxis *axis)
 void LogXLogYDomain::handleVerticalAxisBaseChanged(qreal baseY)
 {
     m_logBaseY = baseY;
-    qreal logMinY = std::log10(m_minY) / std::log10(m_logBaseY);
-    qreal logMaxY = std::log10(m_maxY) / std::log10(m_logBaseY);
+    qreal logMinY = qLn(m_minY) / qLn(m_logBaseY);
+    qreal logMaxY = qLn(m_maxY) / qLn(m_logBaseY);
     m_logLeftY = logMinY < logMaxY ? logMinY : logMaxY;
     m_logRightY = logMinY > logMaxY ? logMinY : logMaxY;
     emit updated();
@@ -270,8 +270,8 @@ void LogXLogYDomain::handleVerticalAxisBaseChanged(qreal baseY)
 void LogXLogYDomain::handleHorizontalAxisBaseChanged(qreal baseX)
 {
     m_logBaseX = baseX;
-    qreal logMinX = std::log10(m_minX) / std::log10(m_logBaseX);
-    qreal logMaxX = std::log10(m_maxX) / std::log10(m_logBaseX);
+    qreal logMinX = qLn(m_minX) / qLn(m_logBaseX);
+    qreal logMaxX = qLn(m_maxX) / qLn(m_logBaseX);
     m_logLeftX = logMinX < logMaxX ? logMinX : logMaxX;
     m_logRightX = logMinX > logMaxX ? logMinX : logMaxX;
     emit updated();
diff --git a/src/charts/domain/logxlogypolardomain.cpp b/src/charts/domain/logxlogypolardomain.cpp
index 1654b946..fc128851 100644
--- a/src/charts/domain/logxlogypolardomain.cpp
+++ b/src/charts/domain/logxlogypolardomain.cpp
@@ -1,6 +1,6 @@
 /****************************************************************************
 **
-** Copyright (C) 2016 The Qt Company Ltd.
+** Copyright (C) 2021 The Qt Company Ltd.
 ** Contact: https://www.qt.io/licensing/
 **
 ** This file is part of the Qt Charts module of the Qt Toolkit.
@@ -62,8 +62,8 @@ void LogXLogYPolarDomain::setRange(qreal minX, qreal maxX, qreal minY, qreal max
         m_minX = minX;
         m_maxX = maxX;
         axisXChanged = true;
-        qreal logMinX = std::log10(m_minX) / std::log10(m_logBaseX);
-        qreal logMaxX = std::log10(m_maxX) / std::log10(m_logBaseX);
+        qreal logMinX = qLn(m_minX) / qLn(m_logBaseX);
+        qreal logMaxX = qLn(m_maxX) / qLn(m_logBaseX);
         m_logLeftX = logMinX < logMaxX ? logMinX : logMaxX;
         m_logRightX = logMinX > logMaxX ? logMinX : logMaxX;
         if (!m_signalsBlocked)
@@ -74,8 +74,8 @@ void LogXLogYPolarDomain::setRange(qreal minX, qreal maxX, qreal minY, qreal max
         m_minY = minY;
         m_maxY = maxY;
         axisYChanged = true;
-        qreal logMinY = std::log10(m_minY) / std::log10(m_logBaseY);
-        qreal logMaxY = std::log10(m_maxY) / std::log10(m_logBaseY);
+        qreal logMinY = qLn(m_minY) / qLn(m_logBaseY);
+        qreal logMaxY = qLn(m_maxY) / qLn(m_logBaseY);
         m_logInnerY = logMinY < logMaxY ? logMinY : logMaxY;
         m_logOuterY = logMinY > logMaxY ? logMinY : logMaxY;
         if (!m_signalsBlocked)
@@ -155,7 +155,7 @@ qreal LogXLogYPolarDomain::toAngularCoordinate(qreal value, bool &ok) const
     } else {
         ok =  true;
         const qreal tickSpan = 360.0 / qAbs(m_logRightX - m_logLeftX);
-        const qreal logValue = std::log10(value) / std::log10(m_logBaseX);
+        const qreal logValue = qLn(value) / qLn(m_logBaseX);
         const qreal valueDelta = logValue - m_logLeftX;
 
         retVal = valueDelta * tickSpan;
@@ -172,7 +172,7 @@ qreal LogXLogYPolarDomain::toRadialCoordinate(qreal value, bool &ok) const
     } else {
         ok =  true;
         const qreal tickSpan = m_radius / qAbs(m_logOuterY - m_logInnerY);
-        const qreal logValue = std::log10(value) / std::log10(m_logBaseY);
+        const qreal logValue = qLn(value) / qLn(m_logBaseY);
         const qreal valueDelta = logValue - m_logInnerY;
 
         retVal = valueDelta * tickSpan;
@@ -234,8 +234,8 @@ bool LogXLogYPolarDomain::detachAxis(QAbstractAxis *axis)
 void LogXLogYPolarDomain::handleHorizontalAxisBaseChanged(qreal baseX)
 {
     m_logBaseX = baseX;
-    qreal logMinX = std::log10(m_minX) / std::log10(m_logBaseX);
-    qreal logMaxX = std::log10(m_maxX) / std::log10(m_logBaseX);
+    qreal logMinX = qLn(m_minX) / qLn(m_logBaseX);
+    qreal logMaxX = qLn(m_maxX) / qLn(m_logBaseX);
     m_logLeftX = logMinX < logMaxX ? logMinX : logMaxX;
     m_logRightX = logMinX > logMaxX ? logMinX : logMaxX;
     emit updated();
@@ -244,8 +244,8 @@ void LogXLogYPolarDomain::handleHorizontalAxisBaseChanged(qreal baseX)
 void LogXLogYPolarDomain::handleVerticalAxisBaseChanged(qreal baseY)
 {
     m_logBaseY = baseY;
-    qreal logMinY = std::log10(m_minY) / std::log10(m_logBaseY);
-    qreal logMaxY = std::log10(m_maxY) / std::log10(m_logBaseY);
+    qreal logMinY = qLn(m_minY) / qLn(m_logBaseY);
+    qreal logMaxY = qLn(m_maxY) / qLn(m_logBaseY);
     m_logInnerY = logMinY < logMaxY ? logMinY : logMaxY;
     m_logOuterY = logMinY > logMaxY ? logMinY : logMaxY;
     emit updated();
diff --git a/src/charts/domain/logxydomain.cpp b/src/charts/domain/logxydomain.cpp
index 09f474c3..5a09fee8 100644
--- a/src/charts/domain/logxydomain.cpp
+++ b/src/charts/domain/logxydomain.cpp
@@ -1,6 +1,6 @@
 /****************************************************************************
 **
-** Copyright (C) 2016 The Qt Company Ltd.
+** Copyright (C) 2021 The Qt Company Ltd.
 ** Contact: https://www.qt.io/licensing/
 **
 ** This file is part of the Qt Charts module of the Qt Toolkit.
@@ -58,8 +58,8 @@ void LogXYDomain::setRange(qreal minX, qreal maxX, qreal minY, qreal maxY)
         m_minX = minX;
         m_maxX = maxX;
         axisXChanged = true;
-        qreal logMinX = std::log10(m_minX) / std::log10(m_logBaseX);
-        qreal logMaxX = std::log10(m_maxX) / std::log10(m_logBaseX);
+        qreal logMinX = qLn(m_minX) / qLn(m_logBaseX);
+        qreal logMaxX = qLn(m_maxX) / qLn(m_logBaseX);
         m_logLeftX = logMinX < logMaxX ? logMinX : logMaxX;
         m_logRightX = logMinX > logMaxX ? logMinX : logMaxX;
         if(!m_signalsBlocked)
@@ -162,7 +162,7 @@ QPointF LogXYDomain::calculateGeometryPoint(const QPointF &point, bool &ok) cons
     if (!m_reverseY)
         y = m_size.height() - y;
     if (point.x() > 0) {
-        x = ((std::log10(point.x()) / std::log10(m_logBaseX)) - m_logLeftX) * deltaX;
+        x = ((qLn(point.x()) / qLn(m_logBaseX)) - m_logLeftX) * deltaX;
         if (m_reverseX)
             x = m_size.width() - x;
         ok = true;
@@ -184,7 +184,7 @@ QList<QPointF> LogXYDomain::calculateGeometryPoints(const QList<QPointF> &list)
 
     for (int i = 0; i < list.count(); ++i) {
         if (list[i].x() > 0) {
-            qreal x = ((std::log10(list[i].x()) / std::log10(m_logBaseX)) - m_logLeftX) * deltaX;
+            qreal x = ((qLn(list[i].x()) / qLn(m_logBaseX)) - m_logLeftX) * deltaX;
             if (m_reverseX)
                 x = m_size.width() - x;
             qreal y = (list[i].y() - m_minY) * deltaY;
@@ -239,8 +239,8 @@ bool LogXYDomain::detachAxis(QAbstractAxis *axis)
 void LogXYDomain::handleHorizontalAxisBaseChanged(qreal baseX)
 {
     m_logBaseX = baseX;
-    qreal logMinX = std::log10(m_minX) / std::log10(m_logBaseX);
-    qreal logMaxX = std::log10(m_maxX) / std::log10(m_logBaseX);
+    qreal logMinX = qLn(m_minX) / qLn(m_logBaseX);
+    qreal logMaxX = qLn(m_maxX) / qLn(m_logBaseX);
     m_logLeftX = logMinX < logMaxX ? logMinX : logMaxX;
     m_logRightX = logMinX > logMaxX ? logMinX : logMaxX;
     emit updated();
diff --git a/src/charts/domain/logxypolardomain.cpp b/src/charts/domain/logxypolardomain.cpp
index 3c0140dc..11236d38 100644
--- a/src/charts/domain/logxypolardomain.cpp
+++ b/src/charts/domain/logxypolardomain.cpp
@@ -1,6 +1,6 @@
 /****************************************************************************
 **
-** Copyright (C) 2016 The Qt Company Ltd.
+** Copyright (C) 2021 The Qt Company Ltd.
 ** Contact: https://www.qt.io/licensing/
 **
 ** This file is part of the Qt Charts module of the Qt Toolkit.
@@ -58,8 +58,8 @@ void LogXYPolarDomain::setRange(qreal minX, qreal maxX, qreal minY, qreal maxY)
         m_minX = minX;
         m_maxX = maxX;
         axisXChanged = true;
-        qreal logMinX = std::log10(m_minX) / std::log10(m_logBaseX);
-        qreal logMaxX = std::log10(m_maxX) / std::log10(m_logBaseX);
+        qreal logMinX = qLn(m_minX) / qLn(m_logBaseX);
+        qreal logMaxX = qLn(m_maxX) / qLn(m_logBaseX);
         m_logLeftX = logMinX < logMaxX ? logMinX : logMaxX;
         m_logRightX = logMinX > logMaxX ? logMinX : logMaxX;
         if (!m_signalsBlocked)
@@ -148,7 +148,7 @@ qreal LogXYPolarDomain::toAngularCoordinate(qreal value, bool &ok) const
     } else {
         ok =  true;
         const qreal tickSpan = 360.0 / qAbs(m_logRightX - m_logLeftX);
-        const qreal logValue = std::log10(value) / std::log10(m_logBaseX);
+        const qreal logValue = qLn(value) / qLn(m_logBaseX);
         const qreal valueDelta = logValue - m_logLeftX;
 
         retVal = valueDelta * tickSpan;
@@ -213,8 +213,8 @@ bool LogXYPolarDomain::detachAxis(QAbstractAxis *axis)
 void LogXYPolarDomain::handleHorizontalAxisBaseChanged(qreal baseX)
 {
     m_logBaseX = baseX;
-    qreal logMinX = std::log10(m_minX) / std::log10(m_logBaseX);
-    qreal logMaxX = std::log10(m_maxX) / std::log10(m_logBaseX);
+    qreal logMinX = qLn(m_minX) / qLn(m_logBaseX);
+    qreal logMaxX = qLn(m_maxX) / qLn(m_logBaseX);
     m_logLeftX = logMinX < logMaxX ? logMinX : logMaxX;
     m_logRightX = logMinX > logMaxX ? logMinX : logMaxX;
     emit updated();
diff --git a/src/charts/domain/xlogydomain.cpp b/src/charts/domain/xlogydomain.cpp
index 21f7d761..c8bbcce9 100644
--- a/src/charts/domain/xlogydomain.cpp
+++ b/src/charts/domain/xlogydomain.cpp
@@ -1,6 +1,6 @@
 /****************************************************************************
 **
-** Copyright (C) 2016 The Qt Company Ltd.
+** Copyright (C) 2021 The Qt Company Ltd.
 ** Contact: https://www.qt.io/licensing/
 **
 ** This file is part of the Qt Charts module of the Qt Toolkit.
@@ -66,8 +66,8 @@ void XLogYDomain::setRange(qreal minX, qreal maxX, qreal minY, qreal maxY)
         m_minY = minY;
         m_maxY = maxY;
         axisYChanged = true;
-        qreal logMinY = std::log10(m_minY) / std::log10(m_logBaseY);
-        qreal logMaxY = std::log10(m_maxY) / std::log10(m_logBaseY);
+        qreal logMinY = qLn(m_minY) / qLn(m_logBaseY);
+        qreal logMaxY = qLn(m_maxY) / qLn(m_logBaseY);
         m_logLeftY = logMinY < logMaxY ? logMinY : logMaxY;
         m_logRightY = logMinY > logMaxY ? logMinY : logMaxY;
         if (!m_signalsBlocked)
@@ -162,7 +162,7 @@ QPointF XLogYDomain::calculateGeometryPoint(const QPointF &point, bool &ok) cons
         x = m_size.width() - x;
     qreal y(0);
     if (point.y() > 0) {
-        y = ((std::log10(point.y()) / std::log10(m_logBaseY)) - m_logLeftY) * deltaY;
+        y = ((qLn(point.y()) / qLn(m_logBaseY)) - m_logLeftY) * deltaY;
         if (!m_reverseY)
             y = m_size.height() - y;
         ok = true;
@@ -187,7 +187,7 @@ QList<QPointF> XLogYDomain::calculateGeometryPoints(const QList<QPointF> &list)
             qreal x = (list[i].x() - m_minX) * deltaX;
             if (m_reverseX)
                 x = m_size.width() - x;
-            qreal y = ((std::log10(list[i].y()) / std::log10(m_logBaseY)) - m_logLeftY) * deltaY;
+            qreal y = ((qLn(list[i].y()) / qLn(m_logBaseY)) - m_logLeftY) * deltaY;
             if (!m_reverseY)
                 y = m_size.height() - y;
             result[i].setX(x);
@@ -236,8 +236,8 @@ bool XLogYDomain::detachAxis(QAbstractAxis *axis)
 void XLogYDomain::handleVerticalAxisBaseChanged(qreal baseY)
 {
     m_logBaseY = baseY;
-    qreal logMinY = std::log10(m_minY) / std::log10(m_logBaseY);
-    qreal logMaxY = std::log10(m_maxY) / std::log10(m_logBaseY);
+    qreal logMinY = qLn(m_minY) / qLn(m_logBaseY);
+    qreal logMaxY = qLn(m_maxY) / qLn(m_logBaseY);
     m_logLeftY = logMinY < logMaxY ? logMinY : logMaxY;
     m_logRightY = logMinY > logMaxY ? logMinY : logMaxY;
     emit updated();
diff --git a/src/charts/domain/xlogypolardomain.cpp b/src/charts/domain/xlogypolardomain.cpp
index 0b72ff84..3c05245f 100644
--- a/src/charts/domain/xlogypolardomain.cpp
+++ b/src/charts/domain/xlogypolardomain.cpp
@@ -1,6 +1,6 @@
 /****************************************************************************
 **
-** Copyright (C) 2016 The Qt Company Ltd.
+** Copyright (C) 2021 The Qt Company Ltd.
 ** Contact: https://www.qt.io/licensing/
 **
 ** This file is part of the Qt Charts module of the Qt Toolkit.
@@ -66,8 +66,8 @@ void XLogYPolarDomain::setRange(qreal minX, qreal maxX, qreal minY, qreal maxY)
         m_minY = minY;
         m_maxY = maxY;
         axisYChanged = true;
-        qreal logMinY = std::log10(m_minY) / std::log10(m_logBaseY);
-        qreal logMaxY = std::log10(m_maxY) / std::log10(m_logBaseY);
+        qreal logMinY = qLn(m_minY) / qLn(m_logBaseY);
+        qreal logMaxY = qLn(m_maxY) / qLn(m_logBaseY);
         m_logInnerY = logMinY < logMaxY ? logMinY : logMaxY;
         m_logOuterY = logMinY > logMaxY ? logMinY : logMaxY;
         if (!m_signalsBlocked)
@@ -156,7 +156,7 @@ qreal XLogYPolarDomain::toRadialCoordinate(qreal value, bool &ok) const
     } else {
         ok =  true;
         const qreal tickSpan = m_radius / qAbs(m_logOuterY - m_logInnerY);
-        const qreal logValue = std::log10(value) / std::log10(m_logBaseY);
+        const qreal logValue = qLn(value) / qLn(m_logBaseY);
         const qreal valueDelta = logValue - m_logInnerY;
 
         retVal = valueDelta * tickSpan;
@@ -208,8 +208,8 @@ bool XLogYPolarDomain::detachAxis(QAbstractAxis *axis)
 void XLogYPolarDomain::handleVerticalAxisBaseChanged(qreal baseY)
 {
     m_logBaseY = baseY;
-    qreal logMinY = std::log10(m_minY) / std::log10(m_logBaseY);
-    qreal logMaxY = std::log10(m_maxY) / std::log10(m_logBaseY);
+    qreal logMinY = qLn(m_minY) / qLn(m_logBaseY);
+    qreal logMaxY = qLn(m_maxY) / qLn(m_logBaseY);
     m_logInnerY = logMinY < logMaxY ? logMinY : logMaxY;
     m_logOuterY = logMinY > logMaxY ? logMinY : logMaxY;
     emit updated();