diff options
Diffstat (limited to 'CSMath/src/bisection/DualExpr.java')
| -rw-r--r-- | CSMath/src/bisection/DualExpr.java | 270 |
1 files changed, 0 insertions, 270 deletions
diff --git a/CSMath/src/bisection/DualExpr.java b/CSMath/src/bisection/DualExpr.java deleted file mode 100644 index 0c76840..0000000 --- a/CSMath/src/bisection/DualExpr.java +++ /dev/null @@ -1,270 +0,0 @@ -package bisection;
-
-/**
- * Represents an expression using dual numbers.
- *
- * Useful for automatically differentiating expressions.
- */
-public class DualExpr {
- /**
- * Represents the various types of dual expressions.
- */
- public static enum ExprType {
- /**
- * A fixed number.
- */
- CONSTANT,
- /**
- * An addition operation.
- */
- ADDITION,
- /**
- * A subtraction operation.
- */
- SUBTRACTION,
- /**
- * A multiplication operation.
- */
- MULTIPLICATION,
- /**
- * A division operation.
- */
- DIVISION,
- /**
- * A sine operation.
- */
- SIN,
- /**
- * A cosine operation.
- */
- COS,
- /**
- * An exponential function.
- */
- EXPONENTIAL,
- /**
- * A logarithm function.
- */
- LOGARITHM,
- /**
- * A power operation.
- */
- POWER,
- /**
- * An absolute value.
- */
- ABSOLUTE
- }
-
- /**
- * The type of the expression.
- */
- public final DualExpr.ExprType type;
-
- /**
- * The dual number value, for constants.
- */
- public Dual number;
-
- /**
- * The left (or first) part of the expression.
- */
- public DualExpr left;
- /**
- * The right (or second) part of the expression.
- */
- public DualExpr right;
-
- /**
- * The power to use, for power operations.
- */
- public int power;
-
- /**
- * Create a new constant dual number.
- *
- * @param num
- * The value of the dual number.
- */
- public DualExpr(Dual num) {
- this.type = ExprType.CONSTANT;
-
- number = num;
- }
-
- /**
- * Create a new unary dual number.
- *
- * @param type
- * The type of operation to perform.
- * @param val
- * The parameter to the value.
- */
- public DualExpr(DualExpr.ExprType type, DualExpr val) {
- this.type = type;
-
- left = val;
- }
-
- /**
- * Create a new math expression.
- * - * The type of operation to perform.
- * @param left
- * The left operand
- * @param right
- * The right operand - */
- public DualExpr(DualExpr.ExprType type, DualExpr left, DualExpr right) {
- this.type = type;
-
- this.left = left;
- this.right = right;
- }
-
- /**
- * Create a new power expression.
- *
- * @param left
- * The expression to raise.
- * @param power
- * The power to raise it by.
- */
- public DualExpr(DualExpr left, int power) {
- this.type = ExprType.POWER;
-
- this.left = left;
- this.power = power;
- }
-
- /**
- * Evaluate an expression to a number.
- *
- * Uses the rules provided in
- * https://en.wikipedia.org/wiki/Automatic_differentiation
- *
- * @return The evaluated expression.
- */
- public Dual evaluate() {
- /* The evaluated dual numbers. */
- Dual lval, rval;
-
- /* Perform the right operation for each type. */
- switch (type) {
- case CONSTANT:
- return number;
- case ADDITION:
- lval = left.evaluate();
- rval = right.evaluate();
-
- return new Dual(lval.real + rval.real, lval.dual + rval.dual);
- case SUBTRACTION:
- lval = left.evaluate();
- rval = right.evaluate();
-
- return new Dual(lval.real - rval.real, lval.dual - rval.dual);
- case MULTIPLICATION:
- lval = left.evaluate();
- rval = right.evaluate();
-
- {
- double lft = lval.dual * rval.real;
- double rght = lval.real * rval.dual;
-
- return new Dual(lval.real * rval.real, lft + rght);
- }
- case DIVISION:
- lval = left.evaluate();
- rval = right.evaluate();
-
- {
- if (rval.real == 0) {
- throw new IllegalArgumentException("ERROR: Attempted to divide by zero.");
- }
-
- double lft = lval.dual * rval.real;
- double rght = lval.real * rval.dual;
-
- double val = (lft - rght) / (rval.real * rval.real);
-
- return new Dual(lval.real / rval.real, val);
- }
- case SIN:
- lval = left.evaluate();
-
- return new Dual(Math.sin(lval.real), lval.dual * Math.cos(lval.real));
- case COS:
- lval = left.evaluate();
-
- return new Dual(Math.cos(lval.real), -lval.dual * Math.sin(lval.real));
- case EXPONENTIAL:
- lval = left.evaluate();
-
- {
- double val = Math.exp(lval.real);
-
- return new Dual(val, lval.dual * val);
- }
- case LOGARITHM:
- lval = left.evaluate();
-
- if (lval.real <= 0) {
- throw new IllegalArgumentException("ERROR: Attempted to take non-positive log.");
- }
-
- return new Dual(Math.log(lval.real), lval.dual / lval.real);
- case POWER:
- lval = left.evaluate();
-
- if (lval.real == 0) {
- throw new IllegalArgumentException("ERROR: Raising zero to a power.");
- }
-
- {
- double rl = Math.pow(lval.real, power);
-
- double lft = Math.pow(lval.real, power - 1);
-
- return new Dual(rl, power * lft * lval.dual);
- }
- case ABSOLUTE:
- lval = left.evaluate();
-
- return new Dual(Math.abs(lval.real), lval.dual * Math.signum(lval.real));
- default:
- String msg = "ERROR: Unknown expression type %s";
-
- throw new IllegalArgumentException(String.format(msg, type));
- }
- }
-
- @Override
- public String toString() {
- switch (type) {
- case ABSOLUTE:
- return String.format("abs(%s)", left.toString());
- case ADDITION:
- return String.format("(%s + %s)", left.toString(), right.toString());
- case CONSTANT:
- return String.format("%s", number.toString());
- case COS:
- return String.format("cos(%s)", left.toString());
- case DIVISION:
- return String.format("(%s / %s)", left.toString(), right.toString());
- case EXPONENTIAL:
- return String.format("exp(%s)", left.toString());
- case LOGARITHM:
- return String.format("log(%s)", left.toString());
- case MULTIPLICATION:
- return String.format("(%s * %s)", left.toString(), right.toString());
- case POWER:
- return String.format("(%s ^ %d)", left.toString(), power);
- case SIN:
- return String.format("sin(%s)", left.toString());
- case SUBTRACTION:
- return String.format("(%s - %s)", left.toString(), right.toString());
- default:
- return String.format("UNKNOWN_EXPR");
- }
- }
-}
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