From 9c3330cb6d651fc97a0443538b1b830b243b3723 Mon Sep 17 00:00:00 2001
From: Iaroslav Postovalov <postovalovya@gmail.com>
Date: Sun, 13 Sep 2020 17:02:30 +0700
Subject: [PATCH] Implement decimal benchmark, update field implementation

---
 .../kmath/bignum/BigDecimalBenchmark.kt       | 41 +++++++++++++++++++
 .../kmath/bignum/BigIntegerBenchmark.kt       |  2 +-
 .../kmath/bignum/BigDecimalField.kt           | 18 +++++---
 3 files changed, 54 insertions(+), 7 deletions(-)
 create mode 100644 examples/src/benchmarks/kotlin/scientifik/kmath/bignum/BigDecimalBenchmark.kt

diff --git a/examples/src/benchmarks/kotlin/scientifik/kmath/bignum/BigDecimalBenchmark.kt b/examples/src/benchmarks/kotlin/scientifik/kmath/bignum/BigDecimalBenchmark.kt
new file mode 100644
index 000000000..12dd060c0
--- /dev/null
+++ b/examples/src/benchmarks/kotlin/scientifik/kmath/bignum/BigDecimalBenchmark.kt
@@ -0,0 +1,41 @@
+package scientifik.kmath.bignum
+
+import org.openjdk.jmh.annotations.Benchmark
+import org.openjdk.jmh.annotations.Scope
+import org.openjdk.jmh.annotations.State
+import scientifik.kmath.operations.JBigDecimalField
+import scientifik.kmath.operations.invoke
+import kotlin.random.Random
+
+@State(Scope.Benchmark)
+class BigDecimalBenchmark {
+    final var times: Int = 10000
+
+    @Benchmark
+    fun java() {
+        val random = Random(0)
+        var sum = JBigDecimalField.zero
+
+        repeat(times) {
+            sum += JBigDecimalField {
+                number(random.nextDouble(-1000000000.0, 1000000000.0)) / random.nextDouble(-1000000.0, 1000000.0)
+            }
+        }
+
+        println("java:$sum")
+    }
+
+    @Benchmark
+    fun bignum() {
+        val random = Random(0)
+        var sum = BigDecimalField.zero
+
+        repeat(times) {
+            sum += BigDecimalField {
+                number(random.nextDouble(-1000000000.0, 1000000000.0)) / random.nextDouble(-1000000.0, 1000000.0)
+            }
+        }
+
+        println("bignum:$sum")
+    }
+}
diff --git a/examples/src/benchmarks/kotlin/scientifik/kmath/bignum/BigIntegerBenchmark.kt b/examples/src/benchmarks/kotlin/scientifik/kmath/bignum/BigIntegerBenchmark.kt
index fca4e22ba..d9a609016 100644
--- a/examples/src/benchmarks/kotlin/scientifik/kmath/bignum/BigIntegerBenchmark.kt
+++ b/examples/src/benchmarks/kotlin/scientifik/kmath/bignum/BigIntegerBenchmark.kt
@@ -10,7 +10,7 @@ import kotlin.random.Random
 
 @State(Scope.Benchmark)
 class BigIntegerBenchmark {
-    var times: Int = 1000000
+    final var times: Int = 1000000
 
     @Benchmark
     fun java() {
diff --git a/kmath-bignum/src/commonMain/kotlin/scientifik/kmath/bignum/BigDecimalField.kt b/kmath-bignum/src/commonMain/kotlin/scientifik/kmath/bignum/BigDecimalField.kt
index 507c8c163..ddca93dd7 100644
--- a/kmath-bignum/src/commonMain/kotlin/scientifik/kmath/bignum/BigDecimalField.kt
+++ b/kmath-bignum/src/commonMain/kotlin/scientifik/kmath/bignum/BigDecimalField.kt
@@ -2,9 +2,10 @@ package scientifik.kmath.bignum
 
 import com.ionspin.kotlin.bignum.decimal.BigDecimal
 import com.ionspin.kotlin.bignum.decimal.DecimalMode
+import com.ionspin.kotlin.bignum.decimal.RoundingMode
 import scientifik.kmath.operations.Field
 
-abstract class BigDecimalFieldBase internal constructor(val mode: DecimalMode = DecimalMode.DEFAULT) :
+abstract class BigDecimalFieldBase internal constructor(val mode: DecimalMode = DEFAULT_MODE) :
     Field<BigDecimal> {
     override val zero: BigDecimal
         get() = BigDecimal.ZERO
@@ -17,12 +18,17 @@ abstract class BigDecimalFieldBase internal constructor(val mode: DecimalMode =
     override fun multiply(a: BigDecimal, k: Number): BigDecimal = a.times(number(k))
     override fun multiply(a: BigDecimal, b: BigDecimal): BigDecimal = a.times(b)
     override fun divide(a: BigDecimal, b: BigDecimal): BigDecimal = a.divide(b)
-    override fun BigDecimal.times(k: Number): BigDecimal = times(number(k))
-    override fun BigDecimal.plus(b: Number): BigDecimal = plus(number(b))
-    override fun BigDecimal.minus(b: Number): BigDecimal = minus(number(b))
-    override fun BigDecimal.div(k: Number): BigDecimal = div(number(k))
+    override fun BigDecimal.minus(b: BigDecimal): BigDecimal = subtract(b, mode)
+    override fun BigDecimal.times(k: Number): BigDecimal = multiply(number(k), mode)
+    override fun BigDecimal.plus(b: Number): BigDecimal = add(number(b), mode)
+    override fun BigDecimal.minus(b: Number): BigDecimal = subtract(number(b), mode)
+    override fun BigDecimal.div(k: Number): BigDecimal = divide(number(k), mode)
+
+    companion object {
+        internal val DEFAULT_MODE = DecimalMode(16, RoundingMode.ROUND_HALF_AWAY_FROM_ZERO)
+    }
 }
 
-class BigDecimalField(mode: DecimalMode = DecimalMode.DEFAULT) : BigDecimalFieldBase(mode) {
+class BigDecimalField(mode: DecimalMode = DEFAULT_MODE) : BigDecimalFieldBase(mode) {
     companion object : BigDecimalFieldBase()
 }