1 files changed, 44 insertions, 0 deletions
diff --git a/src/decimal-round.h b/src/decimal-round.h
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--- /dev/null
+++ b/src/decimal-round.h
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+#ifndef SEEN_DECIMAL_ROUND_H
+#define SEEN_DECIMAL_ROUND_H
+
+#include <cmath>
+
+#include "round.h"
+
+
+namespace Inkscape {
+
+/** Returns x rounded to the nearest \a nplaces decimal places.
+
+    Implemented in terms of Inkscape::round, i.e. we make no guarantees as to what happens if x is
+    half way between two rounded numbers.  Add a note to the documentation if you care which
+    candidate is chosen for such case (round towards -infinity, +infinity, 0, or "even").
+
+    Note: nplaces is the number of decimal places without using scientific (e) notation, not the
+    number of significant figures.  This function may not be suitable for values of x whose
+    magnitude is so far from 1 that one would want to use scientific (e) notation.
+
+    The current implementation happens to allow nplaces to be negative: e.g. nplaces=-2 means
+    rounding to a multiple of 100.  May or may not be useful.
+**/
+inline double
+decimal_round(double const x, int const nplaces)
+{
+    double const multiplier = std::pow(10.0, nplaces);
+    return Inkscape::round( x * multiplier ) / multiplier;
+}
+
+}
+
+#endif /* !SEEN_DECIMAL_ROUND_H */
+
+/*
+  Local Variables:
+  mode:c++
+  c-file-style:"stroustrup"
+  c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
+  indent-tabs-mode:nil
+  fill-column:99
+  End:
+*/
+// vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4 :