Charts: internationalise representation of scientific format.

It seems that when representing real numbers in scientific
notation, there are several cultural conventions. This change
allows the translators to choose the convention best suited
to their locale.

diff --git a/src/math/chart-geometry.c b/src/math/chart-geometry.c
index f74c0aaf9ca31a5ef98fef5682c629d436a62c90..cf377a70e28c0e1903c17524620d5a96641e6250 100644 (file)
--- a/src/math/chart-geometry.c
+++ b/src/math/chart-geometry.c
@@ -26,6 +26,9 @@
 #include "gl/minmax.h"
 #include "gl/xvasprintf.h"
 
+#include "gettext.h"
+#define _(msgid) gettext (msgid)
+
 static const double standard_tick[] = {1, 2, 5, 10};
 
 /* 
@@ -87,6 +90,39 @@ chart_get_scale (double high, double low,
     }
 }
 
+/* 
+   Generate a format string which can be passed to printf like functions,
+   which will produce a string in scientific notation representing a real 
+   number.  N_DECIMALS is the number of decimal places EXPONENT is the 
+   value of the exponent.
+*/
+static inline char *
+gen_pango_markup_scientific_format_string (int n_decimals, int exponent)
+{
+  /* TRANSLATORS: This is a format string which, when presented to
+     printf like functions, will create a pango markup string to
+     display real number in scientific  notation. 
+     
+     In its untranslated form, it will display similar to "1.23 x 10^4". You 
+     can leave it untranslated if this is how scientific notation is usually
+     presented in your language.
+     
+     Some locales (such as German) prefer the centered dot rather than the
+     multiplication sign between the mantissa an exponent. In which
+     case, you can change "#215;" to "#8901;" or other unicode code
+     point as appropriate. 
+
+     The . in this string does not and should not be changed, since
+     that is taken care of by the stdc library. 
+
+     For information on Pango markup, see 
+     http://developer.gnome.org/pango/stable/PangoMarkupFormat.html
+
+     For tables of unicode code points, see http://unicode.org/charts
+   */
+  return xasprintf(_("%%.%dlf&#215;10<sup>%d</sup>"), n_decimals, exponent);
+}
+
 /*
  * Compute the optimum format string and the scaling
  * for the tick drawing on a chart axis
@@ -138,7 +174,7 @@ chart_get_ticks_format (const double lower, const double interval,
          /* log10(0.2E9) = 8.30, log10(0.5E9) = 8.69, log10(1.0E9) = 9    */
          /* 0.2 and 0.5 need one decimal more. For stability subtract 0.1 */
          nrdecs = MIN(8,(int)(ceil(logshift-logintv-0.1)));
-         format_string = xasprintf("%%.%dlf&#215;10<sup>%d</sup>",nrdecs,logshift);
+         format_string = gen_pango_markup_scientific_format_string (nrdecs, logshift);
        }
     }
   else /* logmax and logintv are < 0 */
@@ -153,9 +189,9 @@ chart_get_ticks_format (const double lower, const double interval,
        {
          logshift = (int)logmax-1;
          nrdecs = MIN(8,(int)(ceil(logshift-logintv-0.1)));
-         format_string = xasprintf("%%.%dlf&#215;10<sup>%d</sup>",nrdecs,logshift);
+         format_string = gen_pango_markup_scientific_format_string (nrdecs, logshift);
        }
-    }
+      }
   *scale = pow(10.0,-(double)logshift);
   return format_string;
 }