fixed some issues with Decimals

lynglib/src/commonTest/kotlin/net/sergeych/lyng/BigDecimalModuleTest.kt

@@ -146,4 +146,84 @@ class BigDecimalModuleTest {
             assertEquals("0.2", s0.toString())
         """.trimIndent())
     }
+
+    @Test
+    fun testDecimalMathHelpersUseExactImplementationsWhenAvailable() = runTest {
+        val scope = Script.newScope()
+        scope.eval(
+            """
+            import lyng.decimal
+
+            val absValue = abs("-2.5".d) as BigDecimal
+            val floorPos = floor("2.9".d) as BigDecimal
+            val floorNeg = floor("-2.1".d) as BigDecimal
+            val ceilPos = ceil("2.1".d) as BigDecimal
+            val ceilNeg = ceil("-2.1".d) as BigDecimal
+            val roundPos = round("2.5".d) as BigDecimal
+            val roundNeg = round("-2.5".d) as BigDecimal
+            val powInt = pow("1.5".d, 2) as BigDecimal
+
+            assertEquals("2.5", absValue.toStringExpanded())
+            assertEquals("2", floorPos.toStringExpanded())
+            assertEquals("-3", floorNeg.toStringExpanded())
+            assertEquals("3", ceilPos.toStringExpanded())
+            assertEquals("-2", ceilNeg.toStringExpanded())
+            assertEquals("3", roundPos.toStringExpanded())
+            assertEquals("-2", roundNeg.toStringExpanded())
+            assertEquals("2.25", powInt.toStringExpanded())
+            """.trimIndent()
+        )
+    }
+
+    @Test
+    fun testDecimalMathHelpersFallbackThroughRealTemporarily() = runTest {
+        val scope = Script.newScope()
+        scope.eval(
+            """
+            import lyng.decimal
+
+            val sinDecimal = sin("0.5".d) as BigDecimal
+            val expDecimal = exp("1.25".d) as BigDecimal
+            val sqrtDecimal = sqrt("2".d) as BigDecimal
+            val lnDecimal = ln("2".d) as BigDecimal
+            val log10Decimal = log10("2".d) as BigDecimal
+            val log2Decimal = log2("2".d) as BigDecimal
+            val powDecimal = pow("2".d, "0.5".d) as BigDecimal
+
+            assertEquals((sin(0.5) as Real).d.toStringExpanded(), sinDecimal.toStringExpanded())
+            assertEquals((exp(1.25) as Real).d.toStringExpanded(), expDecimal.toStringExpanded())
+            assertEquals((sqrt(2.0) as Real).d.toStringExpanded(), sqrtDecimal.toStringExpanded())
+            assertEquals((ln(2.0) as Real).d.toStringExpanded(), lnDecimal.toStringExpanded())
+            assertEquals((log10(2.0) as Real).d.toStringExpanded(), log10Decimal.toStringExpanded())
+            assertEquals((log2(2.0) as Real).d.toStringExpanded(), log2Decimal.toStringExpanded())
+            assertEquals((pow(2.0, 0.5) as Real).d.toStringExpanded(), powDecimal.toStringExpanded())
+            """.trimIndent()
+        )
+    }
+
+    @Test
+    fun decimalMustBeObj() = runTest {
+        eval("""
+            import lyng.decimal
+
+            val decimal = 42.d
+            val context = DecimalContext(12)
+
+            assert(decimal is BigDecimal)
+            assertEquals(BigDecimal, decimal::class)
+
+            assert(context is DecimalContext)
+            assertEquals(DecimalContext, context::class)
+        """.trimIndent())
+    }
+
+    @Test
+    fun testFromRealLife1() = runTest {
+        eval("""
+            import lyng.decimal
+            var X = 42.d
+            X += 11
+            assertEquals(53.d, X)
+        """)
+    }
 }

lynglib/src/commonTest/kotlin/net/sergeych/lyng/MatrixModuleTest.kt

@@ -152,4 +152,20 @@ class MatrixModuleTest {
             """.trimIndent()
         )
     }
+
+    @Test
+    fun matrixAndVectorMustBeObjs() = runTest {
+        eval("""
+            import lyng.matrix
+
+            val matrixValue = matrix([[1, 2], [3, 4]])
+            val vectorValue = vector([1, 2, 3])
+
+            assert(matrixValue is Matrix)
+            assertEquals(Matrix, matrixValue::class)
+
+            assert(vectorValue is Vector)
+            assertEquals(Vector, vectorValue::class)
+        """.trimIndent())
+    }
 }

lynglib/src/commonTest/kotlin/net/sergeych/lyng/RandomModuleTest.kt

@@ -0,0 +1,33 @@
+/*
+ * Copyright 2026 Sergey S. Chernov real.sergeych@gmail.com
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package net.sergeych.lyng
+
+import kotlinx.coroutines.test.runTest
+import kotlin.test.Test
+
+class RandomModuleTest {
+    @Test
+    fun seededRandomMustBeObj() = runTest {
+        eval("""
+            val rng = Random.seeded(12345)
+
+            assert(rng is SeededRandom)
+            assertEquals(SeededRandom, rng::class)
+        """.trimIndent())
+    }
+}