tdf#70673 Power trendline: enable negative Y values

With a negative intercept, Y values can be negative

Change-Id: I9c23cc89b74498f7e7c7bcee00057627768f48aa
Reviewed-on: https://gerrit.libreoffice.org/15357
Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Philippe Jung <phil.jung@free.fr>

1 files changed, 13 insertions, 0 deletions

diff --git a/chart2/source/inc/RegressionCalculationHelper.hxx b/chart2/source/inc/RegressionCalculationHelper.hxx
index 2e0e3a4adc53..7f0a69368467 100644
--- a/chart2/source/inc/RegressionCalculationHelper.hxx
+++ b/chart2/source/inc/RegressionCalculationHelper.hxx
@@ -127,6 +127,19 @@ public:
     }
 };
 
+class isValidAndXPositiveAndYNegative : public ::std::binary_function< double, double, bool >
+{
+public:
+    inline bool operator()( double x, double y )
+    { return ! ( ::rtl::math::isNan( x ) ||
+                 ::rtl::math::isNan( y ) ||
+                 ::rtl::math::isInf( x ) ||
+                 ::rtl::math::isInf( y ) ||
+                 x <= 0.0 ||
+                 y >= 0.0 );
+    }
+};
+
 } //  namespace RegressionCalculationHelper
 } //  namespace chart