update GALLERY.md (complex_arithmetic)

GALLERY.md

@@ -12,6 +12,7 @@ This gallery shows examples from all available datasets using their default conf
 - [calendar_arithmetic](#calendar_arithmetic)
 - [chain_sum](#chain_sum)
 - [color_cube_rotation](#color_cube_rotation)
+- [complex_arithmetic](#complex_arithmetic)
 - [countdown](#countdown)
 - [course_schedule](#course_schedule)
 - [family_relationships](#family_relationships)
@@ -487,6 +488,39 @@ Metadata: {'initial_state': {'top': 'orange', 'right': 'cyan', 'front': 'violet'
 
 ````
 
+### complex_arithmetic
+Generates complex number arithmetic problems.
+
+Default configuration:
+```python
+min_real = -10
+max_real = 10
+min_imag = -10
+max_imag = 10
+operations = ('+', '-', '*', '/')
+seed = 42
+size = 500
+```
+
+Example tasks:
+````
+Example 1:
+Question: Subtract the complex numbers: (10 - 7i) - (-10 - 2i)
+Answer: 20 - 5i
+Metadata: {'num1': (10.0, -7.0), 'num2': (-10.0, -2.0), 'operation': '-', 'result': (20.0, -5.0)}
+
+Example 2:
+Question: Multiply the complex numbers: (-9 - 1i) × (-6 + 4i)
+Answer: 58 - 30i
+Metadata: {'num1': (-9.0, -1.0), 'num2': (-6.0, 4.0), 'operation': '*', 'result': (58.0, -30.0)}
+
+Example 3:
+Question: Subtract the complex numbers: (3 + 6i) - (7 - 7i)
+Answer: -4 + 13i
+Metadata: {'num1': (3.0, 6.0), 'num2': (7.0, -7.0), 'operation': '-', 'result': (-4.0, 13.0)}
+
+````
+
 ### countdown
 Generates Countdown Number Game tasks
 
@@ -2111,7 +2145,7 @@ Metadata: {'task_type': 'datetime_tz', 'start_time': datetime.datetime(2964, 6,
 Example 2:
 Question: A video call started at 09:44 and ended at 12:22. How long was the call? Answer in HH:MM.
 Answer: 02:38
-Metadata: {'task_type': 'time', 'start_time': datetime.datetime(2025, 2, 5, 9, 44), 'end_time': datetime.datetime(2025, 2, 5, 12, 22), 'format': '%H:%M', 'expected_format': 'HH:MM'}
+Metadata: {'task_type': 'time', 'start_time': datetime.datetime(2025, 2, 6, 9, 44), 'end_time': datetime.datetime(2025, 2, 6, 12, 22), 'format': '%H:%M', 'expected_format': 'HH:MM'}
 
 Example 3:
 Question: Calculate the time difference between Sat Dec 22 2677 and Thu Mar 21 2678. Express the result in D days.