boost::optional<Quantity> QuantityConverterSingleton::convert(const Quantity &original,
const Unit& targetUnits) const
{
Quantity working(original);
OptionalQuantity candidate;
// See if nothing to be done. (Check for equality of system and base units + exponents.)
if ((working.system() == targetUnits.system()) && (working.units() == targetUnits))
{
// Assume targetUnits has desired scale.
working.setScale(targetUnits.scale().exponent);
return working;
}
// All conversions go through SI
if (working.system() != UnitSystem::SI) {
candidate = m_convertToSI(working);
if (!candidate) {
return boost::none;
}
working = *candidate;
}
// Retain pretty string
OptionalQuantity result = m_convertToTargetFromSI(working,targetUnits);
if (result &&
result->prettyUnitsString(false).empty() &&
!targetUnits.prettyString(false).empty())
{
result->setPrettyUnitsString(targetUnits.prettyString(false));
}
return result;
}
TEST_F(UnitsFixture,QuantityConverter_PowerDensity) {
Quantity siLpd(10.0,createSIPowerDensity());
Unit ipPowerDensity = createUnit("W/ft^2").get();
OptionalQuantity ipLpd = convert(siLpd,ipPowerDensity);
Quantity siArea(1.0,pow(createSILength(),2));
OptionalQuantity ipArea = convert(siArea,UnitSystem(UnitSystem::IP));
ASSERT_TRUE(ipLpd);
ASSERT_TRUE(ipArea);
EXPECT_NEAR(10.0/ipArea->value(),ipLpd->value(),tol);
EXPECT_EQ("W/ft^2",ipLpd->prettyUnitsString());
}
TEST_F(UnitsFixture,QuantityConverter_BTUandIPUsingSystem)
{
LOG(Debug, "QuantityConverter_BTUandIPUsingSystem");
UnitSystem siSys(UnitSystem::SI);
UnitSystem ipSys(UnitSystem::IP);
UnitSystem btuSys(UnitSystem::BTU);
// uses BTU to SI, SI to IP
BTUUnit btuu1(openstudio::BTUExpnt(1,-2,0,0), 3);
Quantity bQ( 67.5, btuu1 );
testStreamOutput("67.5 kBtu/ft^2",bQ);
OptionalQuantity ipQ = QuantityConverter::instance().convert( bQ, ipSys);
EXPECT_TRUE(ipQ);
if (ipQ) {
EXPECT_EQ("lb_m/s^2",ipQ->standardUnitsString(false));
EXPECT_EQ("klb_m/s^2",ipQ->standardUnitsString());
SCOPED_TRACE("btu1 to IP");
testNumbersEqual(1689985.20448, ipQ->value());
}
BTUUnit btuu2(openstudio::BTUExpnt(0,0,-1));
bQ = Quantity(5000.0, btuu2);
ipQ = QuantityConverter::instance().convert( bQ, ipSys);
EXPECT_TRUE(ipQ);
if (ipQ) {
SCOPED_TRACE("bQ to IP, 1");
testStreamOutput("1.3889 1/s",*ipQ,4);
}
bQ *= bQ; // 25E6/h^2
ipQ = QuantityConverter::instance().convert( bQ, ipSys);
EXPECT_TRUE(ipQ);
if (ipQ) {
SCOPED_TRACE("bQ to IP, 2");
testStreamOutput("1.9290 1/s^2",*ipQ,4);
}
BTUUnit btuu3(openstudio::BTUExpnt(-1),-3);
bQ = Quantity(1.0, btuu3);
testStreamOutput("1 1/kBtu",bQ);
OptionalQuantity siQ = QuantityConverter::instance().convert(bQ,siSys);
EXPECT_TRUE(siQ);
if (siQ) {
EXPECT_EQ("1/J",siQ->prettyUnitsString(false));
SCOPED_TRACE("btu3 to SI");
testNumbersEqual(9.478171203133172e-4,siQ->value());
siQ->setScale(0);
SCOPED_TRACE("rescaled btu3 to SI");
testNumbersEqual(9.478171203133172e-7,siQ->value());
}
// uses IP to SI, SI to BTU
IPUnit ipu1(openstudio::IPExpnt(0,1,0,-1,0,0,0,1), -2);
Quantity ipQ2( 2.0, ipu1);
OptionalQuantity bQ2 = QuantityConverter::instance().convert( ipQ2, btuSys);
EXPECT_TRUE(bQ2);
if (bQ2) {
EXPECT_EQ("Btu/R", bQ2->standardUnitsString(false));
EXPECT_EQ("cBtu/R", bQ2->standardUnitsString());
SCOPED_TRACE("ipu1 to BTU");
testNumbersEqual(0.002570134927, bQ2->value(),1.0e-5);
bQ2->setScale(0);
EXPECT_EQ("Btu/R", bQ2->standardUnitsString());
testNumbersEqual(2.570134927e-5, bQ2->value(),1.0e-5);
}
}