chsX method Null safety

void chsX()

Negate the value in x like the CHS key does. The behavior varies according to the current sign mode. In complex mode, it leaves the imaginary part alone, and does not change the CLX status.


void chsX() {
  _stack[0] = signMode.negate(x, this);
  needsSave = true;
  display.window = 0;