Method hold

src/compute-engine/index.ts:1793–1795

* Add a `["Hold"]` wrapper to `expr`.

(expr: ExpressionInput)

  chop(n: BigDecimal): BigDecimal | 0;
  chop(n: Complex): Complex | 0;
  chop(n: number | BigDecimal | Complex): number | BigDecimal | Complex {
    const tolerance = this._numericConfiguration.tolerance;
    if (typeof n === 'number') {
      if (Math.abs(n) <= tolerance) return 0;
      return n;
    }