Function is_valid_second_derivative

src/DataStructures.cpp:312–358

}

bool is_valid_second_derivative(const std::string& name, parameters& iOf1, parameters& iWrt1, parameters& iConstant1, parameters& iWrt2,
                                parameters& iConstant2) {
    if (get_debug_level() > 5) {
        std::cout << format("is_valid_second_derivative(%s)", name.c_str());
    }

    // Suppose we start with "d(d(P)/d(Dmolar)|T)/d(Dmolar)|T"
    std::size_t i = name.rfind('|');
    if ((i == 0) || (i == std::string::npos)) {
        return false;
    }
    std::string constant2 = name.substr(i + 1);  // "T"
    if (!is_valid_parameter(constant2, iConstant2)) {
        return false;
    };
    std::string left_of_bar = name.substr(0, i);  // "d(d(P)/d(Dmolar)|T)/d(Dmolar)"

    i = left_of_bar.rfind('/');
    if ((i == 0) || (i == std::string::npos)) {
        return false;
    }
    std::string left_of_slash = left_of_bar.substr(0, i);    // "d(d(P)/d(Dmolar)|T)"
    std::string right_of_slash = left_of_bar.substr(i + 1);  // "d(Dmolar)"

    i = left_of_slash.find('(');
    std::size_t i1 = left_of_slash.rfind(')');
    if (!((i > 0) && (i != std::string::npos) && (i1 > (i + 1)) && (i1 != std::string::npos))) {
        return false;
    }
    std::string num = left_of_slash.substr(i + 1, i1 - i - 1);  // "d(P)/d(Dmolar)|T"
    if (!is_valid_first_derivative(num, iOf1, iWrt1, iConstant1)) {
        return false;
    }

    i = right_of_slash.find('(');
    i1 = right_of_slash.rfind(')');
    if (!((i > 0) && (i != std::string::npos) && (i1 > (i + 1)) && (i1 != std::string::npos))) {
        return false;
    }
    std::string den = right_of_slash.substr(i + 1, i1 - i - 1);  // "Dmolar"
    if (!is_valid_parameter(den, iWrt2)) {
        return false;
    }

    // If we haven't quit yet, all is well
    return true;
}

struct phase_info
{