void Quantity::lbmToLbf()
{
OptionalIPUnit iu = m_units.optionalCast<IPUnit>();
if(!iu) {
LOG_AND_THROW("Cannot convert non-IP quantity " << *this << " in system "
<< system().valueName() << " from pound-mass to pound-force.");
}
// convert from (value * lb_m^x * ...) to (value * lb_f^x * ...)
// lb_m^x * (1/gc)^x = lb_f^x * s^{2x} / ft^x
int x = baseUnitExponent("lb_m");
if (x != 0) {
iu->lbmToLbf();
m_value /= std::pow(IPUnit::gc(),x);
}
BOOST_ASSERT(baseUnitExponent("lb_m") == 0);
}
bool Unit_Impl::operator==(const Unit& rUnit) const {
// construct union of base units
StringSet allBaseUnits;
StringVector baseUnits;
baseUnits = this->baseUnits();
allBaseUnits.insert(baseUnits.begin(),baseUnits.end());
baseUnits = rUnit.baseUnits();
allBaseUnits.insert(baseUnits.begin(),baseUnits.end());
// loop through and see if exponents are equal
BOOST_FOREACH(const std::string& baseUnit,allBaseUnits) {
if (baseUnitExponent(baseUnit) != rUnit.baseUnitExponent(baseUnit)) {
return false;
}
}
return true;
}
Quantity& Quantity::operator-=(const Quantity& temp) {
if (this == &temp) {
m_value = 0.0;
return *this;
}
// copy input reference so we can change its properties
Quantity rQuantity(temp);
if (isTemperature() && rQuantity.isTemperature()) {
if (isAbsolute() && rQuantity.isAbsolute()) {
// units must be the same, check that exponent on this is 1
std::vector<std::string> bus = baseUnits();
OS_ASSERT(bus.size() == 1);
if (baseUnitExponent(bus[0]) == 1) {
setAsRelative();
rQuantity.setAsRelative();
}
} else if (!isAbsolute() && rQuantity.isAbsolute()) {
setAsAbsolute();
} else if (isAbsolute() && !rQuantity.isAbsolute()) {
rQuantity.setAsAbsolute();
}
}
if (m_units != rQuantity.m_units) {
LOG_AND_THROW("Cannot subtract quantities with different units.");
}
if (scale() != rQuantity.scale()) {
Quantity wRQuantity(rQuantity);
wRQuantity.setScale(scale().exponent);
m_value -= wRQuantity.value();
}
else {
m_value -= rQuantity.value();
}
return *this;
}
