1 files changed, 186 insertions, 0 deletions
diff --git a/chart2/source/tools/LogarithmicRegressionCurveCalculator.cxx b/chart2/source/tools/LogarithmicRegressionCurveCalculator.cxx
new file mode 100644
index 000000000..ffd1808df
--- /dev/null
+++ b/chart2/source/tools/LogarithmicRegressionCurveCalculator.cxx
@@ -0,0 +1,186 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/*
+ * This file is part of the LibreOffice project.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ *
+ * This file incorporates work covered by the following license notice:
+ *
+ *   Licensed to the Apache Software Foundation (ASF) under one or more
+ *   contributor license agreements. See the NOTICE file distributed
+ *   with this work for additional information regarding copyright
+ *   ownership. The ASF licenses this file to you under the Apache
+ *   License, Version 2.0 (the "License"); you may not use this file
+ *   except in compliance with the License. You may obtain a copy of
+ *   the License at http://www.apache.org/licenses/LICENSE-2.0 .
+ */
+
+#include <LogarithmicRegressionCurveCalculator.hxx>
+#include <RegressionCalculationHelper.hxx>
+#include <SpecialCharacters.hxx>
+
+#include <rtl/math.hxx>
+#include <rtl/ustrbuf.hxx>
+
+using namespace ::com::sun::star;
+
+namespace chart
+{
+
+LogarithmicRegressionCurveCalculator::LogarithmicRegressionCurveCalculator() :
+        m_fSlope( std::numeric_limits<double>::quiet_NaN() ),
+        m_fIntercept( std::numeric_limits<double>::quiet_NaN() )
+{
+}
+
+LogarithmicRegressionCurveCalculator::~LogarithmicRegressionCurveCalculator()
+{}
+
+// ____ XRegressionCurve ____
+void SAL_CALL LogarithmicRegressionCurveCalculator::recalculateRegression(
+    const uno::Sequence< double >& aXValues,
+    const uno::Sequence< double >& aYValues )
+{
+    RegressionCalculationHelper::tDoubleVectorPair aValues(
+        RegressionCalculationHelper::cleanup(
+            aXValues, aYValues,
+            RegressionCalculationHelper::isValidAndXPositive()));
+
+    const size_t nMax = aValues.first.size();
+    if( nMax <= 1 )  // at least 2 points
+    {
+        m_fSlope = std::numeric_limits<double>::quiet_NaN();
+        m_fIntercept = std::numeric_limits<double>::quiet_NaN();
+        m_fCorrelationCoefficient = std::numeric_limits<double>::quiet_NaN();
+        return;
+    }
+
+    double fAverageX = 0.0, fAverageY = 0.0;
+    size_t i = 0;
+    for( i = 0; i < nMax; ++i )
+    {
+        fAverageX += log( aValues.first[i] );
+        fAverageY += aValues.second[i];
+    }
+
+    const double fN = static_cast< double >( nMax );
+    fAverageX /= fN;
+    fAverageY /= fN;
+
+    double fQx = 0.0, fQy = 0.0, fQxy = 0.0;
+    for( i = 0; i < nMax; ++i )
+    {
+        double fDeltaX = log( aValues.first[i] ) - fAverageX;
+        double fDeltaY = aValues.second[i] - fAverageY;
+
+        fQx  += fDeltaX * fDeltaX;
+        fQy  += fDeltaY * fDeltaY;
+        fQxy += fDeltaX * fDeltaY;
+    }
+
+    m_fSlope = fQxy / fQx;
+    m_fIntercept = fAverageY - m_fSlope * fAverageX;
+    m_fCorrelationCoefficient = fQxy / sqrt( fQx * fQy );
+}
+
+double SAL_CALL LogarithmicRegressionCurveCalculator::getCurveValue( double x )
+{
+    if( ! ( std::isnan( m_fSlope ) ||
+            std::isnan( m_fIntercept )))
+    {
+        return m_fSlope * log( x ) + m_fIntercept;
+    }
+
+    return std::numeric_limits<double>::quiet_NaN();
+}
+
+uno::Sequence< geometry::RealPoint2D > SAL_CALL LogarithmicRegressionCurveCalculator::getCurveValues(
+    double min, double max, ::sal_Int32 nPointCount,
+    const uno::Reference< chart2::XScaling >& xScalingX,
+    const uno::Reference< chart2::XScaling >& xScalingY,
+    sal_Bool bMaySkipPointsInCalculation )
+{
+    if( bMaySkipPointsInCalculation &&
+        isLogarithmicScaling( xScalingX ) &&
+        isLinearScaling( xScalingY ))
+    {
+        // optimize result
+        uno::Sequence< geometry::RealPoint2D > aResult{ { min, getCurveValue( min ) },
+                                                        { max, getCurveValue( max ) } };
+
+        return aResult;
+    }
+    return RegressionCurveCalculator::getCurveValues( min, max, nPointCount, xScalingX, xScalingY, bMaySkipPointsInCalculation );
+}
+
+OUString LogarithmicRegressionCurveCalculator::ImplGetRepresentation(
+    const uno::Reference< util::XNumberFormatter >& xNumFormatter,
+    sal_Int32 nNumberFormatKey, sal_Int32* pFormulaMaxWidth /* = nullptr */ ) const
+{
+    bool bHasSlope = !rtl::math::approxEqual( fabs( m_fSlope ), 1.0 );
+    OUStringBuffer aBuf( mYName + " = " );
+    sal_Int32 nLineLength = aBuf.getLength();
+    sal_Int32 nValueLength=0;
+    if ( pFormulaMaxWidth && *pFormulaMaxWidth > 0 ) // count nValueLength
+    {
+        sal_Int32 nCharMin = nLineLength + 6 + mXName.getLength();  // 6 = "ln(x)" + 2 extra characters
+        if( m_fSlope < 0.0 )
+            nCharMin += 2;  // "- "
+        if( m_fSlope != 0.0 && m_fIntercept != 0.0 )
+        {
+            nCharMin += 3; // " + "
+            if ( bHasSlope )
+                nValueLength = (*pFormulaMaxWidth - nCharMin) / 2;
+        }
+        if ( nValueLength == 0 ) // not yet calculated
+            nValueLength = *pFormulaMaxWidth - nCharMin;
+        if ( nValueLength <= 0 )
+            nValueLength = 1;
+    }
+
+    // temporary buffer
+    OUStringBuffer aTmpBuf("");
+    // if nValueLength not calculated then nullptr
+    sal_Int32* pValueLength = nValueLength ? &nValueLength : nullptr;
+    if( m_fSlope != 0.0 )  // add slope value
+    {
+        if( m_fSlope < 0.0 )
+        {
+            aTmpBuf.append( OUStringChar(aMinusSign) + " " );
+        }
+        if( bHasSlope )
+        {
+            OUString aValueString = getFormattedString( xNumFormatter, nNumberFormatKey, fabs(m_fSlope), pValueLength );
+            if ( aValueString != "1" )  // aValueString may be rounded to 1 if nValueLength is small
+            {
+                aTmpBuf.append( aValueString + " " );
+            }
+        }
+        aTmpBuf.append( "ln(" + mXName + ") " );
+        addStringToEquation( aBuf, nLineLength, aTmpBuf, pFormulaMaxWidth );
+        aTmpBuf.truncate();
+
+        if( m_fIntercept > 0.0 )
+            aTmpBuf.append( "+ " );
+    }
+             // add intercept value
+    if( m_fIntercept < 0.0 )
+        aTmpBuf.append( OUStringChar(aMinusSign) + " " );
+    OUString aValueString = getFormattedString( xNumFormatter, nNumberFormatKey, fabs(m_fIntercept), pValueLength );
+    if ( aValueString != "0" )  // aValueString may be rounded to 0 if nValueLength is small
+    {
+        aTmpBuf.append( aValueString );
+        addStringToEquation( aBuf, nLineLength, aTmpBuf, pFormulaMaxWidth );
+    }
+
+    if ( std::u16string_view(aBuf) == OUStringConcatenation(mYName + " = ") )
+        aBuf.append( "0" );
+
+    return aBuf.makeStringAndClear();
+}
+
+} //  namespace chart
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */