diff options
| author | Benjamin Culkin <bjculkin@mix.wvu.edu> | 2018-02-05 13:01:44 -0800 |
|---|---|---|
| committer | Benjamin Culkin <bjculkin@mix.wvu.edu> | 2018-02-05 13:01:44 -0800 |
| commit | 03e2fc959702e7654c507c4c6125ea1c1b54ecb6 (patch) | |
| tree | 77f898d4fc6d6ae2b5712419d7ccf8aeed263d91 /base/src/main/java/bjc/utils/math/Dual.java | |
| parent | 48ed157c10d045746450a9c775b3342ee55a4ac6 (diff) | |
Add dual numbers
Dual numbers are a easy way of doing automatic numeric differentiation
of expressions.
Diffstat (limited to 'base/src/main/java/bjc/utils/math/Dual.java')
| -rw-r--r-- | base/src/main/java/bjc/utils/math/Dual.java | 83 |
1 files changed, 83 insertions, 0 deletions
diff --git a/base/src/main/java/bjc/utils/math/Dual.java b/base/src/main/java/bjc/utils/math/Dual.java new file mode 100644 index 0000000..53ddc32 --- /dev/null +++ b/base/src/main/java/bjc/utils/math/Dual.java @@ -0,0 +1,83 @@ +package bjc.utils.math;
+
+/**
+ * Represents a 'dual' number.
+ *
+ * Think imaginary numbers, where instead of i, we add a value d such that d^2 =
+ * 0.
+ */
+public class Dual {
+ /**
+ * The real part of the dual number.
+ */
+ public double real;
+ /**
+ * The dual part of the dual number.
+ */
+ public double dual;
+
+ /**
+ * Create a new dual with both parts zero.
+ */
+ public Dual() {
+ real = 0;
+ dual = 0;
+ }
+
+ /**
+ * Create a new dual number with a zero dual part.
+ *
+ * @param real
+ * The real part of the number.
+ */
+ public Dual(double real) {
+ this.real = real;
+ this.dual = 0;
+ }
+
+ /**
+ * Create a new dual number with a specified dual part.
+ *
+ * @param real
+ * The real part of the number.
+ * @param dual
+ * The dual part of the number.
+ */
+ public Dual(double real, double dual) {
+ this.real = real;
+ this.dual = dual;
+ }
+
+ @Override
+ public String toString() {
+ return String.format("<%f, %f>", real, dual);
+ }
+
+ @Override
+ public int hashCode() {
+ final int prime = 31;
+ int result = 1;
+ long temp;
+ temp = Double.doubleToLongBits(dual);
+ result = prime * result + (int) (temp ^ (temp >>> 32));
+ temp = Double.doubleToLongBits(real);
+ result = prime * result + (int) (temp ^ (temp >>> 32));
+ return result;
+ }
+
+ @Override
+ public boolean equals(Object obj) {
+ if (this == obj)
+ return true;
+ if (obj == null)
+ return false;
+ if (getClass() != obj.getClass())
+ return false;
+ Dual other = (Dual) obj;
+ if (Double.doubleToLongBits(dual) != Double.doubleToLongBits(other.dual))
+ return false;
+ if (Double.doubleToLongBits(real) != Double.doubleToLongBits(other.real))
+ return false;
+ return true;
+ }
+}
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