+struct histogram_chart
+ {
+ struct chart_item chart_item;
+ gsl_histogram *gsl_hist;
+ double n;
+ double mean;
+ double stddev;
+ bool show_normal;
+ };
+
+/* Creates and returns a new chart that depicts a histogram of
+ the data in HIST with the given LABEL. Labels the histogram
+ with each of N, MEAN, and STDDEV that is not SYSMIS. If all
+ three are not SYSMIS and SHOW_NORMAL is true, also draws a
+ normal curve on the histogram. */
+struct chart_item *histogram_chart_create (const gsl_histogram *,
+ const char *label, double n,
+ double mean, double stddev,
+ bool show_normal);
+\f
+/* This boilerplate for histogram_chart, a subclass of chart_item, was
+ autogenerated by mk-class-boilerplate. */
+
+#include <assert.h>
+#include "libpspp/cast.h"
+
+extern const struct chart_item_class histogram_chart_class;
+
+/* Returns true if SUPER is a histogram_chart, otherwise false. */
+static inline bool
+is_histogram_chart (const struct chart_item *super)
+{
+ return super->class == &histogram_chart_class;
+}
+
+/* Returns SUPER converted to histogram_chart. SUPER must be a histogram_chart, as
+ reported by is_histogram_chart. */
+static inline struct histogram_chart *
+to_histogram_chart (const struct chart_item *super)