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mass based derivatives (I think) plus test

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referenced in https://github.com/CoolProp/CoolProp/issues/177

Signed-off-by: Ian Bell <ian.h.bell@gmail.com>
This commit is contained in:
Ian Bell
2014-10-15 23:09:13 +02:00
parent 1727771411
commit c8fedbbf30
2 changed files with 58 additions and 2 deletions
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18
src/Tests/CoolProp-Tests.cpp
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@@ -972,6 +972,24 @@ TEST_CASE("Test first partial derivatives using PropsSI", "[derivatives]")
CHECK(rel_err_exact < 1e-7);
CHECK(rel_err_approx < 1e-7);
}
SECTION("Check dpdrho|T 3 ways for water using mass based","")
{
T = 80+273.15;
shared_ptr<CoolProp::AbstractState> AS(CoolProp::AbstractState::factory("HEOS", "Water"));
AS->update(CoolProp::PT_INPUTS, 101325, T);
long double rhomass = AS->rhomass();
double dpdrhomass__T_AbstractState = AS->first_partial_deriv(CoolProp::iP, CoolProp::iDmass, CoolProp::iT);
double dpdrhomass__T_PropsSI_num = (PropsSI("P","T",T,"Dmass",rhomass+1e-3,"Water") - PropsSI("P","T",T,"Dmass",rhomass-1e-3,"Water"))/(2*1e-3);
double dpdrhomass__T_PropsSI = PropsSI("d(P)/d(Dmass)|T","T",T,"P",101325,"Water");
CAPTURE(rhomass);
CAPTURE(dpdrhomass__T_AbstractState);
CAPTURE(dpdrhomass__T_PropsSI_num);
CAPTURE(dpdrhomass__T_PropsSI);
double rel_err_exact = std::abs((dpdrhomass__T_AbstractState-dpdrhomass__T_PropsSI)/dpdrhomass__T_PropsSI);
double rel_err_approx = std::abs((dpdrhomass__T_PropsSI_num-dpdrhomass__T_PropsSI)/dpdrhomass__T_PropsSI);
CHECK(rel_err_exact < 1e-7);
CHECK(rel_err_approx < 1e-7);
}
SECTION("Invalid first partial derivatives","")
{
CHECK(!ValidNumber(PropsSI("d()/d(P)|T","T",300,"P",101325,"n-Propane")));