diff --git a/src/libiso8601/calc.c b/src/libiso8601/calc.c
index 6381274..3c0ac11 100644
--- a/src/libiso8601/calc.c
+++ b/src/libiso8601/calc.c
@@ -295,6 +295,31 @@ int iso8601_from_cal(struct iso8601_date* date, int year, int month, int day)
 
 
 
+int iso8601_from_ord(struct iso8601_date* date, int year, int oday)
+{
+    // check for domain errors
+    if(oday < 1 || oday > (iso8601_isleap(year) ? 366 : 365)) {
+        errno = EDOM;
+        return -1;
+    }
+
+    // perform year calculation
+    if(_from_year(date, year)) return -1;
+
+    // now simply add number of days elapsed this year
+    date->day += oday - 1;
+
+    return 0;
+}
+
+
+
+int iso8601_from_week(struct iso8601_date* date, int isoyear, int week, int wday)
+{
+}
+
+
+
 /* options for text editors
 kate: replace-trailing-space-save true; space-indent true; tab-width 4;
 vim: expandtab:ts=4:sw=4
diff --git a/src/tests/printer.c b/src/tests/printer.c
index bd5c2b9..1b7a7b6 100644
--- a/src/tests/printer.c
+++ b/src/tests/printer.c
@@ -142,6 +142,28 @@ void do_details_ordinal(struct iso8601_details* dt_out, const struct iso8601_det
     dt_out->date_prec = iso8601_prec_ord;
 }
 
+void do_details_week(struct iso8601_details* dt_out, const struct iso8601_details* dt_in)
+{
+    memcpy(dt_out, dt_in, sizeof(struct iso8601_details));
+    dt_out->tz_sec = 0;
+    dt_out->date_prec = iso8601_prec_week;
+}
+
+void do_details_week_day(struct iso8601_details* dt_out, const struct iso8601_details* dt_in)
+{
+    memcpy(dt_out, dt_in, sizeof(struct iso8601_details));
+    dt_out->tz_sec = 0;
+    dt_out->date_prec = iso8601_prec_wday;
+    dt_out->time_prec = iso8601_prec_none;
+}
+
+void do_details_week_full(struct iso8601_details* dt_out, const struct iso8601_details* dt_in)
+{
+    memcpy(dt_out, dt_in, sizeof(struct iso8601_details));
+    dt_out->tz_sec = 0;
+    dt_out->date_prec = iso8601_prec_wday;
+}
+
 
 
 struct test {
@@ -169,6 +191,9 @@ const struct test tests[] = {
     { "Local year", do_details_local_year },
     { "Ordinal date", do_details_ordinal_date },
     { "Ordinal full", do_details_ordinal },
+    { "Week number", do_details_week },
+    { "Week date", do_details_week_day },
+    { "Week full", do_details_week_full },
     { 0, 0 }
 };