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Derivative.java
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158 lines (142 loc) · 3.45 KB
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package symjava.symbolic;
import java.util.ArrayList;
import java.util.List;
import symjava.symbolic.utils.Utils;
public class Derivative extends Func {
Func func = null;
List<Expr> dxyz = new ArrayList<Expr>();
public Derivative(Func f, Expr x) {
super("", f.args);
//Member variable 'expr' in func here is the expression after taking derivative
if(f.expr != null)
this.expr = f.expr.diff(x);
this.func = f;
this.dxyz.add(x);
this.label = "D" + f.label + "D" + getDxyzLabel();
this.sortKey = label;
}
public Derivative(Derivative df, Expr x) {
super("", df.args);
if(df.expr != null)
this.expr = df.expr.diff(x);
this.func = df.func;
this.dxyz.addAll(df.dxyz);
this.dxyz.add(x);
this.label = df.label + x.label;
this.sortKey = label;
}
public Derivative(Func f, Expr[] xs) {
super("", f.args);
if(f.expr != null) {
this.expr = f.expr;
for(Expr x : xs)
this.expr = this.expr.diff(x);
}
this.func = f;
for(Expr x : xs)
this.dxyz.add(x);
this.label = "D" + f.label + "D" + getDxyzLabel();
this.sortKey = label;
}
// public Derivative(Derivative other) {
// super("", other.args);
// this.expr = other.expr;
// this.dxyz.addAll(other.dxyz);
// this.func = other.func;
// this.label = other.label;
// this.sortKey = other.sortKey;
// }
public static Expr simplifiedIns(Func f, Expr x) {
if(f.expr == null)
return new Derivative(f, x);
return f.expr.diff(x);
}
protected String getDxyzLabel() {
StringBuilder sb = new StringBuilder();
for(Expr e : dxyz) {
sb.append(e.toString());
}
return sb.toString();
}
@Override
public Expr diff(Expr expr) {
if(this.expr != null)
return this.expr.diff(expr);
else if(Utils.symCompare(this, expr)) {
return Symbol.C1;
} else if(!this.containsArg(expr) && expr instanceof Symbol) {
return Symbol.C0;
}
return new Derivative(this, expr);
}
@Override
public Expr simplify() {
if(this.expr != null) {
return this.expr.simplify();
}
return this;
}
@Override
public boolean symEquals(Expr other) {
if(other instanceof Derivative) {
Derivative o = (Derivative)other;
Boolean rlt = Utils.symCompareNull(this.expr, o.expr);
if(rlt != null && rlt == false)
return false;
if(!this.label.equals(o.label))
return false;
if(this.args.length != o.args.length)
return false;
for(int i=0; i<this.args.length; i++) {
if(!Utils.symCompare(this.args[i],o.args[i]))
return false;
}
if(this.dxyz.size() != o.dxyz.size())
return false;
for(int i=0; i<this.dxyz.size(); i++) {
if(!Utils.symCompare(this.dxyz.get(i), o.dxyz.get(i)))
return false;
}
return true;
}
return false;
}
@Override
public void flattenAdd(List<Expr> outList) {
if(expr != null)
expr.flattenAdd(outList);
else
outList.add(this);
}
@Override
public void flattenMultiply(List<Expr> outList) {
if(expr != null)
expr.flattenMultiply(outList);
else
outList.add(this);
}
@Override
public Expr subs(Expr from, Expr to) {
if(Utils.symCompare(this, from)) {
return to;
} else if(expr != null) {
return expr.subs(from, to);
} else if(Utils.symCompare(func, from)) {
if(to instanceof Func) {
Derivative rlt = new Derivative((Func)to,
this.dxyz.toArray(new Expr[0])
);
return rlt;
} else {
Expr diffExpr = to;
for(Expr x : dxyz)
diffExpr = diffExpr.diff(x);
return diffExpr;
}
}
return this;
}
public Func getFunc() {
return func;
}
}