From 415d11749aee1caa8aefbf102b0b89baa8976195 Mon Sep 17 00:00:00 2001
From: Iaroslav <postovalovya@gmail.com>
Date: Sun, 28 Jun 2020 22:06:50 +0700
Subject: [PATCH] Improve big arithmetics algebra in JVM module of kmath-core

---
 .../kmath/asm/internal/AsmBuilder.kt          |  2 +-
 .../scientifik/kmath/operations/BigNumbers.kt | 45 ++++++++++++++-----
 2 files changed, 35 insertions(+), 12 deletions(-)

diff --git a/kmath-ast/src/jvmMain/kotlin/scientifik/kmath/asm/internal/AsmBuilder.kt b/kmath-ast/src/jvmMain/kotlin/scientifik/kmath/asm/internal/AsmBuilder.kt
index 5531fd5dc..f3ee81c1c 100644
--- a/kmath-ast/src/jvmMain/kotlin/scientifik/kmath/asm/internal/AsmBuilder.kt
+++ b/kmath-ast/src/jvmMain/kotlin/scientifik/kmath/asm/internal/AsmBuilder.kt
@@ -340,7 +340,7 @@ internal class AsmBuilder<T> internal constructor(
         checkcast(type)
     }
 
-    fun loadNumeric(value: Number) {
+    internal fun loadNumeric(value: Number) {
         if (expectationStack.peek() == NUMBER_TYPE) {
             loadNumberConstant(value, true)
             expectationStack.pop()
diff --git a/kmath-core/src/jvmMain/kotlin/scientifik/kmath/operations/BigNumbers.kt b/kmath-core/src/jvmMain/kotlin/scientifik/kmath/operations/BigNumbers.kt
index e6f09c040..1c1c0a5bf 100644
--- a/kmath-core/src/jvmMain/kotlin/scientifik/kmath/operations/BigNumbers.kt
+++ b/kmath-core/src/jvmMain/kotlin/scientifik/kmath/operations/BigNumbers.kt
@@ -7,31 +7,54 @@ import java.math.MathContext
 /**
  * A field wrapper for Java [BigInteger]
  */
-object JBigIntegerField : Field<BigInteger> {
-    override val zero: BigInteger = BigInteger.ZERO
-    override val one: BigInteger = BigInteger.ONE
+object JBigIntegerRing : Ring<BigInteger>, PowerOperations<BigInteger> {
+    override val zero: BigInteger
+        get() = BigInteger.ZERO
+
+    override val one: BigInteger
+        get() = BigInteger.ONE
 
     override fun add(a: BigInteger, b: BigInteger): BigInteger = a.add(b)
-
+    override fun BigInteger.minus(b: BigInteger): BigInteger = this.subtract(b)
     override fun multiply(a: BigInteger, k: Number): BigInteger = a.multiply(k.toInt().toBigInteger())
-
     override fun multiply(a: BigInteger, b: BigInteger): BigInteger = a.multiply(b)
-
-    override fun divide(a: BigInteger, b: BigInteger): BigInteger = a.div(b)
+    override fun power(arg: BigInteger, pow: Number): BigInteger = arg.pow(pow.toInt())
+    override fun sqrt(arg: BigInteger): BigInteger = arg.sqrt()
+    override fun BigInteger.unaryMinus(): BigInteger = negate()
 }
 
 /**
  * A Field wrapper for Java [BigDecimal]
  */
-class JBigDecimalField(val mathContext: MathContext = MathContext.DECIMAL64) : Field<BigDecimal> {
-    override val zero: BigDecimal = BigDecimal.ZERO
-    override val one: BigDecimal = BigDecimal.ONE
+abstract class JBigDecimalFieldBase internal constructor(val mathContext: MathContext = MathContext.DECIMAL64) :
+    Field<BigDecimal>,
+    PowerOperations<BigDecimal> {
+    override val zero: BigDecimal
+        get() = BigDecimal.ZERO
+
+    override val one: BigDecimal
+        get() = BigDecimal.ONE
 
     override fun add(a: BigDecimal, b: BigDecimal): BigDecimal = a.add(b)
+    override fun BigDecimal.minus(b: BigDecimal): BigDecimal {
+        return subtract(b)
+    }
 
     override fun multiply(a: BigDecimal, k: Number): BigDecimal =
         a.multiply(k.toDouble().toBigDecimal(mathContext), mathContext)
 
     override fun multiply(a: BigDecimal, b: BigDecimal): BigDecimal = a.multiply(b, mathContext)
     override fun divide(a: BigDecimal, b: BigDecimal): BigDecimal = a.divide(b, mathContext)
-}
\ No newline at end of file
+    override fun power(arg: BigDecimal, pow: Number): BigDecimal = arg.pow(pow.toInt(), mathContext)
+    override fun sqrt(arg: BigDecimal): BigDecimal = arg.sqrt(mathContext)
+    override fun BigDecimal.unaryMinus(): BigDecimal = negate(mathContext)
+
+}
+
+class JBigDecimalField(mathContext: MathContext = MathContext.DECIMAL64) : JBigDecimalFieldBase(mathContext) {
+    companion object : JBigDecimalFieldBase()
+}
+
+fun main() {
+    JBigDecimalField { one pow 2 }
+}