Function parseIdentifier

src/function/algebra/derivative.js:90–97

(string)

  }

  function parseIdentifier (string) {
    const symbol = parse(string)
    if (!symbol.isSymbolNode) {
      throw new TypeError('Invalid variable. ' +
        `Cannot parse ${JSON.stringify(string)} into a variable in function derivative`)
    }
    return symbol
  }

  const derivative = typed(name, {
    'Node, SymbolNode': plainDerivative,