Added testcases, documentation and addressed comments

.gitmodules

@@ -357,4 +357,3 @@
 [submodule "contrib/pocketfft"]
 	path = contrib/pocketfft
 	url = https://gitlab.mpcdf.mpg.de/mtr/pocketfft.git
-	branch = cpp

contrib/pocketfft-cmake/CMakeLists.txt

@@ -1,3 +1,10 @@
+option (ENABLE_POCKETFFT "Enable pocketfft" ${ENABLE_LIBRARIES})
+
+if (NOT ENABLE_POCKETFFT)
+    message(STATUS "Not using pocketfft")
+    return()
+endif()
+
 add_library(_pocketfft INTERFACE)
 target_include_directories(_pocketfft INTERFACE ${ClickHouse_SOURCE_DIR}/contrib/pocketfft)
 add_library(ch_contrib::pocketfft ALIAS _pocketfft)

docs/en/sql-reference/functions/time-series-functions.md

@@ -0,0 +1,45 @@
+---
+slug: /en/sql-reference/functions/time-series-functions
+sidebar_position: 140
+sidebar_label: Time Series
+---
+
+# Time Series Functions
+
+Below functions are used for time series anlaysis.
+
+## seriesPeriodDetect
+
+Finds the period of the given time series data
+
+**Syntax**
+
+``` sql
+seriesPeriodDetect(series);
+```
+
+**Arguments**
+
+- `series` - An array of numeric values
+
+**Returned value**
+
+- A real value equal to the period of time series
+
+Type: [Float64](../../sql-reference/data-types/float.md).
+
+**Examples**
+
+Query:
+
+``` sql
+SELECT seriesPeriodDetect([1,4,6,1,4,6,1,4,6,1,4,6]) AS print_0;
+```
+
+Result:
+
+``` text
+┌───────────print_0──────┐
+│                      3 │
+└────────────────────────┘
+```

tests/queries/0_stateless/02813_series_period_detect.reference

@@ -1 +1,4 @@
 14
+3
+3
+3

tests/queries/0_stateless/02813_series_period_detect.sql

@@ -1,3 +1,6 @@
 SELECT seriesPeriodDetect([139, 87, 110, 68, 54, 50, 51, 53, 133, 86, 141, 97, 156, 94, 149, 95, 140, 77, 61, 50, 54, 47, 133, 72, 152, 94, 148, 105, 162, 101, 160, 87, 63, 53, 55, 54, 151, 103, 189, 108, 183, 113, 175, 113, 178, 90, 71, 62, 62, 65, 165, 109, 181, 115, 182, 121, 178, 114, 170]);
-SELECT seriesPeriodDetect([NULL, NULL, NULL]); -- { serverError 44 }
-SELECT seriesPeriodDetect([10,20,30,10,202,30,NULL]); -- { serverError 44 }
+SELECT seriesPeriodDetect([10,20,30,10,20,30,10,20,30, 10,20,30,10,20,30,10,20,30,10,20,30]);
+SELECT seriesPeriodDetect([10.1, 20.45, 40.34, 10.1, 20.45, 40.34,10.1, 20.45, 40.34,10.1, 20.45, 40.34,10.1, 20.45, 40.34,10.1, 20.45, 40.34,10.1, 20.45, 40.34, 10.1, 20.45, 40.34]);
+SELECT seriesPeriodDetect([10.1, 10, 400, 10.1, 10, 400, 10.1, 10, 400,10.1, 10, 400,10.1, 10, 400,10.1, 10, 400,10.1, 10, 400,10.1, 10, 400]);
+SELECT seriesPeriodDetect([NULL, NULL, NULL]); -- { serverError ILLEGAL_COLUMN}
+SELECT seriesPeriodDetect([10,20,30,10,202,30,NULL]); -- { serverError ILLEGAL_COLUMN }