diff --git a/integ-test/src/integration/scala/org/opensearch/flint/spark/ppl/FlintSparkPPLEvalITSuite.scala b/integ-test/src/integration/scala/org/opensearch/flint/spark/ppl/FlintSparkPPLEvalITSuite.scala
index 596626698..e10b2e2a6 100644
--- a/integ-test/src/integration/scala/org/opensearch/flint/spark/ppl/FlintSparkPPLEvalITSuite.scala
+++ b/integ-test/src/integration/scala/org/opensearch/flint/spark/ppl/FlintSparkPPLEvalITSuite.scala
@@ -10,7 +10,7 @@ import org.opensearch.sql.ppl.utils.DataTypeTransformer.seq
 import org.apache.spark.sql.{AnalysisException, QueryTest, Row}
 import org.apache.spark.sql.catalyst.analysis.{UnresolvedAttribute, UnresolvedFunction, UnresolvedRelation, UnresolvedStar}
 import org.apache.spark.sql.catalyst.expressions.{Alias, And, Ascending, CaseWhen, Descending, EqualTo, GreaterThanOrEqual, LessThan, Literal, SortOrder}
-import org.apache.spark.sql.catalyst.plans.logical.{Aggregate, Filter, LogicalPlan, Project, Sort}
+import org.apache.spark.sql.catalyst.plans.logical.{Aggregate, Filter, GlobalLimit, LocalLimit, LogicalPlan, Project, Sort}
 import org.apache.spark.sql.streaming.StreamTest
 
 class FlintSparkPPLEvalITSuite
@@ -22,6 +22,7 @@ class FlintSparkPPLEvalITSuite
   /** Test table and index name */
   private val testTable = "spark_catalog.default.flint_ppl_test"
   private val testTableHttpLog = "spark_catalog.default.flint_ppl_test_http_log"
+  private val duplicatesNullableTestTable = "spark_catalog.default.duplicates_nullable_test"
 
   override def beforeAll(): Unit = {
     super.beforeAll()
@@ -29,6 +30,7 @@ class FlintSparkPPLEvalITSuite
     // Create test table
     createPartitionedStateCountryTable(testTable)
     createTableHttpLog(testTableHttpLog)
+    createDuplicationNullableTable(duplicatesNullableTestTable)
   }
 
   protected override def afterEach(): Unit = {
@@ -632,8 +634,45 @@ class FlintSparkPPLEvalITSuite
     EqualTo(Literal(true), and)
   }
 
-  // Todo excluded fields not support yet
+  test("Test eval and signum function") {
+    val frame = sql(s"""
+                       | source = $duplicatesNullableTestTable | fields id | sort id | eval i = pow(-2, id), s = signum(i) | head 5
+                       | """.stripMargin)
+    val rows = frame.collect()
+    val expectedResults: Array[Row] = Array(
+      Row(1, -2d, -1d),
+      Row(2, 4d, 1d),
+      Row(3, -8d, -1d),
+      Row(4, 16d, 1d),
+      Row(5, -32d, -1d))
+    assert(rows.sameElements(expectedResults))
+
+    val logicalPlan: LogicalPlan = frame.queryExecution.logical
+    val tablePlan =
+      UnresolvedRelation(Seq("spark_catalog", "default", "duplicates_nullable_test"))
+    val projectIdPlan = Project(Seq(UnresolvedAttribute("id")), tablePlan)
+    val sortPlan =
+      Sort(Seq(SortOrder(UnresolvedAttribute("id"), Ascending)), global = true, projectIdPlan)
+    val evalPlan = Project(
+      Seq(
+        UnresolvedStar(None),
+        Alias(
+          UnresolvedFunction(
+            "pow",
+            Seq(Literal(-2), UnresolvedAttribute("id")),
+            isDistinct = false),
+          "i")(),
+        Alias(
+          UnresolvedFunction("signum", Seq(UnresolvedAttribute("i")), isDistinct = false),
+          "s")()),
+      sortPlan)
+    val localLimitPlan = LocalLimit(Literal(5), evalPlan)
+    val globalLimitPlan = GlobalLimit(Literal(5), localLimitPlan)
+    val expectedPlan = Project(Seq(UnresolvedStar(None)), globalLimitPlan)
+    comparePlans(logicalPlan, expectedPlan, checkAnalysis = false)
+  }
 
+  // Todo excluded fields not support yet
   ignore("test single eval expression with excluded fields") {
     val frame = sql(s"""
          | source = $testTable | eval new_field = "New Field" | fields - age
diff --git a/ppl-spark-integration/README.md b/ppl-spark-integration/README.md
index f07fcbd3f..6b3996f52 100644
--- a/ppl-spark-integration/README.md
+++ b/ppl-spark-integration/README.md
@@ -333,6 +333,7 @@ Limitation: Overriding existing field is unsupported, following queries throw ex
  - `source = table | eval a = 10 | fields a,b,c`
  - `source = table | eval a = a * 2 | stats avg(a)`
  - `source = table | eval a = abs(a) | where a > 0`
+ - `source = table | eval a = signum(a) | where a < 0`
 
 **Aggregations**
  - `source = table | stats avg(a) `
diff --git a/ppl-spark-integration/src/main/antlr4/OpenSearchPPLLexer.g4 b/ppl-spark-integration/src/main/antlr4/OpenSearchPPLLexer.g4
index 60e1e9922..7af3e2109 100644
--- a/ppl-spark-integration/src/main/antlr4/OpenSearchPPLLexer.g4
+++ b/ppl-spark-integration/src/main/antlr4/OpenSearchPPLLexer.g4
@@ -259,6 +259,7 @@ POWER:                              'POWER';
 RAND:                               'RAND';
 ROUND:                              'ROUND';
 SIGN:                               'SIGN';
+SIGNUM:                             'SIGNUM';
 SQRT:                               'SQRT';
 TRUNCATE:                           'TRUNCATE';
 
diff --git a/ppl-spark-integration/src/main/antlr4/OpenSearchPPLParser.g4 b/ppl-spark-integration/src/main/antlr4/OpenSearchPPLParser.g4
index 626ff2165..385c871cb 100644
--- a/ppl-spark-integration/src/main/antlr4/OpenSearchPPLParser.g4
+++ b/ppl-spark-integration/src/main/antlr4/OpenSearchPPLParser.g4
@@ -568,6 +568,7 @@ mathematicalFunctionName
    | RAND
    | ROUND
    | SIGN
+   | SIGNUM
    | SQRT
    | TRUNCATE
    | trigonometricFunctionName
diff --git a/ppl-spark-integration/src/test/scala/org/opensearch/flint/spark/ppl/PPLLogicalPlanMathFunctionsTranslatorTestSuite.scala b/ppl-spark-integration/src/test/scala/org/opensearch/flint/spark/ppl/PPLLogicalPlanMathFunctionsTranslatorTestSuite.scala
index ed72a3d40..feaa7d8ca 100644
--- a/ppl-spark-integration/src/test/scala/org/opensearch/flint/spark/ppl/PPLLogicalPlanMathFunctionsTranslatorTestSuite.scala
+++ b/ppl-spark-integration/src/test/scala/org/opensearch/flint/spark/ppl/PPLLogicalPlanMathFunctionsTranslatorTestSuite.scala
@@ -191,4 +191,18 @@ class PPLLogicalPlanMathFunctionsTranslatorTestSuite
     val expectedPlan = Project(projectList, evalProject)
     comparePlans(expectedPlan, logPlan, false)
   }
+
+  test("test signum") {
+    val context = new CatalystPlanContext
+    val logPlan = planTransformer.visit(plan(pplParser, "source=t a = signum(b)"), context)
+
+    val table = UnresolvedRelation(Seq("t"))
+    val filterExpr = EqualTo(
+      UnresolvedAttribute("a"),
+      UnresolvedFunction("signum", seq(UnresolvedAttribute("b")), isDistinct = false))
+    val filterPlan = Filter(filterExpr, table)
+    val projectList = Seq(UnresolvedStar(None))
+    val expectedPlan = Project(projectList, filterPlan)
+    comparePlans(expectedPlan, logPlan, false)
+  }
 }