Fix baseAmount used when placing orders (closes #435) (#437)

model/number.go

@@ -18,6 +18,9 @@ var NumberConstants = struct {
 	One:  NumberFromFloat(1.0, 16),
 }
 
+// InvertPrecision is the precision of the number after it is inverted
+const InvertPrecision = 15
+
 // Number abstraction
 type Number struct {
 	value     float64
@@ -131,7 +134,7 @@ func InvertNumber(n *Number) *Number {
 	if n == nil {
 		return nil
 	}
-	return NumberConstants.One.Divide(*n)
+	return NumberFromFloat(1.0/n.AsFloat(), InvertPrecision)
 }
 
 // NumberByCappingPrecision returns a number with a precision that is at max the passed in precision

model/number_test.go

@@ -241,7 +241,7 @@ func TestUnaryOperations(t *testing.T) {
 			n:          NumberFromFloat(0.2812, 3),
 			wantAbs:    0.281,
 			wantNegate: -0.281,
-			wantInvert: 3.559,
+			wantInvert: 3.558718861209964,
 		},
 	}
 
@@ -261,6 +261,9 @@ func TestUnaryOperations(t *testing.T) {
 			if !assert.Equal(t, kase.wantInvert, inverted.AsFloat()) {
 				return
 			}
+			if !assert.Equal(t, int8(15), inverted.precision) {
+				return
+			}
 		})
 	}
 }