Introducing ⊠ as a synonym for the ring module multiplication

appliedtopology · Apr 22, 2024 · eb97842 · eb97842
1 parent 14e68b2
commit eb97842
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Showing 4 changed files with 10 additions and 5 deletions.
diff --git a/src/main/scala/org/appliedtopology/tda4j/Chain.scala b/src/main/scala/org/appliedtopology/tda4j/Chain.scala
@@ -385,7 +385,7 @@ package org.appliedtopology.tda4j {
         scale(-fr.one, x)
 
       override def shows(x: ChainElement[CellT, CoefficientT]): String =
-        x.chainHeap.toList.map((cell, coeff) => s"${coeff.toString} *> ${cell.toString}").mkString(" + ")
+        x.chainHeap.toList.map((cell, coeff) => s"${coeff.toString} ⊠ ${cell.toString}").mkString(" + ")
 
       override def show(x: ChainElement[CellT, CoefficientT]): Cord = Cord(shows(x))
     }

diff --git a/src/main/scala/org/appliedtopology/tda4j/RingModule.scala b/src/main/scala/org/appliedtopology/tda4j/RingModule.scala
@@ -1,5 +1,7 @@
 package org.appliedtopology.tda4j
 
+import scalaz.Show
+
 import scala.annotation.targetName
 
 /** Specifies what it means for the type `T` to be a module (or vector space) over the [Numeric] (ie ring-like) type
@@ -26,12 +28,15 @@ trait RingModule[T, R] {
     def -(rhs: T): T = minus(t, rhs)
     @targetName("scalarMultiplyRight")
     def <*(rhs: R): T = scale(rhs, t)
+    infix def mul(rhs: R): T = scale(rhs,t)
     def unary_- : T = negate(t)
   }
 
   extension (r: R) {
     @targetName("scalarMultiplyLeft")
     def *>(t: T): T = scale(r, t)
+    @targetName("scalarMultiplyLeft2")
+    def ⊠(t:T): T = scale(r,t) // unicode ⊠ for boxed times
   }
 }
 

diff --git a/src/test/scala/org/appliedtopology/tda4j/APISpec.scala b/src/test/scala/org/appliedtopology/tda4j/APISpec.scala
@@ -10,7 +10,7 @@ class APISpec extends mutable.Specification {
   import ctx.{given, *}
 
   "we should be able to create and compute with chains" >> {
-    1.0 *> s(1, 2) - s(2, 3) should beEqualTo(
+    1.0 ⊠ s(1, 2) - s(2, 3) should beEqualTo(
       Chain(Simplex(1, 2) -> 1.0, Simplex(2, 3) -> -1.0)
     )
   }

diff --git a/src/test/scala/org/appliedtopology/tda4j/ChainSpec.scala b/src/test/scala/org/appliedtopology/tda4j/ChainSpec.scala
@@ -199,9 +199,9 @@ class HeapChainSpec extends mutable.Specification {
       given Conversion[Simplex, HeapChain[Simplex, Double]] = HeapChain.apply
       given rm: RingModule[HeapChain[Simplex, Double], Double] = HeapChainOps()
       import rm.{given, *}
-      val z1 = 1.0 *> s(1, 2) + 2.0 *> s(1, 3) - 1.0 *> s(2, 3)
-      val z2 = 1.0 *> s(1, 2) + 1.0 *> s(2, 3)
-      val z3 = z2 + (-1.0 *> z2)
+      val z1 : HeapChain[Simplex,Double] = 1.0 ⊠ s(1, 2) + (s(1, 3) mul 2.0) - 1.0 *> s(2, 3)
+      val z2 : HeapChain[Simplex,Double] = 1.0 ⊠ s(1, 2) + 1.0 ⊠ s(2, 3)
+      val z3 : HeapChain[Simplex,Double] = z2 + (-1.0 ⊠ z2)
 
       "subtracts to zero" ==>
         (z3.isZero must beTrue)