// replace every x in tree by (x - vx)
// i.e. replace fVar with (fvar - vx)
private void translateX(ExpressionNode en, double vx, int varNo) {
ExpressionValue left = en.getLeft();
ExpressionValue right = en.getRight();
// left tree
if (left == fVars[varNo]) {
try { // is there a constant number to the right?
MyDouble num = (MyDouble) right;
double temp;
switch (en.getOperation()) {
case ExpressionNode.PLUS:
temp = num.getDouble() - vx;
if (Kernel.isZero(temp)) {
expression = expression.replaceAndWrap(en, fVars[varNo]);
} else if (temp < 0) {
en.setOperation(ExpressionNode.MINUS);
num.set(-temp);
} else {
num.set(temp);
}
return;
case ExpressionNode.MINUS:
temp = num.getDouble() + vx;
if (Kernel.isZero(temp)) {
expression = expression.replaceAndWrap(en, fVars[varNo]);
} else if (temp < 0) {
en.setOperation(ExpressionNode.PLUS);
num.set(-temp);
} else {
num.set(temp);
}
return;
default:
en.setLeft(shiftXnode(vx, varNo));
}
} catch (Exception e) {
en.setLeft(shiftXnode(vx, varNo));
}
} else if (left instanceof ExpressionNode) {
translateX((ExpressionNode) left, vx, varNo);
}
// right tree
if (right == fVars[varNo]) {
en.setRight(shiftXnode(vx, varNo));
} else if (right instanceof ExpressionNode) {
translateX((ExpressionNode) right, vx, varNo);
}
}
