Provide isInfinite() and isFinite() functions for Double and Float.

#KT-7126 Fixed

libraries/stdlib/src/kotlin/util/Numbers.kt

@@ -10,4 +10,25 @@ public fun Double.isNaN(): Boolean = this != this
  * Returns `true` if the specified number is a
  * Not-a-Number (NaN) value, `false` otherwise.
  */
-public fun Float.isNaN(): Boolean = this != this
+public fun Float.isNaN(): Boolean = this != this
+
+/**
+ * Returns `true` if this value is infinitely large in magnitude.
+ */
+public fun Double.isInfinite(): Boolean = this == Double.POSITIVE_INFINITY || this == Double.NEGATIVE_INFINITY
+
+/**
+ * Returns `true` if this value is infinitely large in magnitude.
+ */
+public fun Float.isInfinite(): Boolean = this == Float.POSITIVE_INFINITY || this == Float.NEGATIVE_INFINITY
+
+/**
+ * Returns `true` if the argument is a finite floating-point value; returns `false` otherwise (for `NaN` and infinity arguments).
+ */
+public fun Double.isFinite(): Boolean = !isInfinite() && !isNaN()
+
+/**
+ * Returns `true` if the argument is a finite floating-point value; returns `false` otherwise (for `NaN` and infinity arguments).
+ */
+public fun Float.isFinite(): Boolean = !isInfinite() && !isNaN()
+

libraries/stdlib/test/numbers/NumbersTest.kt

@@ -0,0 +1,37 @@
+package numbers
+
+import org.junit.Test as test
+import kotlin.test.*
+
+class NumbersTest {
+
+    test fun doubleProperties() {
+        for (value in listOf(1.0, 0.0))
+            doTestNumber(value)
+        for (value in listOf(Double.POSITIVE_INFINITY, Double.NEGATIVE_INFINITY))
+            doTestNumber(value, isInfinite = true)
+        doTestNumber(Double.NaN, isNaN = true)
+    }
+
+    test fun floatProperties() {
+        for (value in listOf(1.0F, 0.0F))
+            doTestNumber(value)
+        for (value in listOf(Float.POSITIVE_INFINITY, Float.NEGATIVE_INFINITY))
+            doTestNumber(value, isInfinite = true)
+        doTestNumber(Float.NaN, isNaN = true)
+    }
+
+
+    private fun doTestNumber(value: Double, isNaN: Boolean = false, isInfinite: Boolean = false) {
+        assertEquals(isNaN, value.isNaN(), "Expected $value to have isNaN: $isNaN")
+        assertEquals(isInfinite, value.isInfinite(), "Expected $value to have isInfinite: $isInfinite")
+        assertEquals(!isNaN && !isInfinite, value.isFinite())
+    }
+
+    private fun doTestNumber(value: Float, isNaN: Boolean = false, isInfinite: Boolean = false) {
+        assertEquals(isNaN, value.isNaN(), "Expected $value to have isNaN: $isNaN")
+        assertEquals(isInfinite, value.isInfinite(), "Expected $value to have isInfinite: $isInfinite")
+        assertEquals(!isNaN && !isInfinite, value.isFinite())
+    }
+
+}