Function someNegTermQ

src/compute-engine/rubi/rubi-utils.ts:1353–1357

(u: Expression)

/** flatten Multiply/Divide/Negate into a factor list (denominator factors
 * become synthetic Power(f, −1) so the RtAux power/odd-exponent logic
 * sees them) */
function rtFactors(u: Expression): Expression[] {
  const ce = u.engine;
  const out: Expression[] = [];
  const walk = (e: Expression, inv: boolean): void => {
    if (e.operator === 'Multiply' && e.ops) {
      for (const f of e.ops) walk(f, inv);
      return;