Disallow setting negative temperature or density

include/cantera/thermo/Phase.h

@@ -543,6 +543,10 @@ public:
     //! Note the density of a phase is an independent variable.
     //!     @param[in] density density (kg/m^3).
     virtual void setDensity(const doublereal density) {
+        if (density <= 0) {
+            throw CanteraError("Phase::setDensity",
+                               "density must be positive");
+        }
         m_dens = density;
     }
 
@@ -553,6 +557,10 @@ public:
     //! Set the internally stored temperature of the phase (K).
     //!     @param temp Temperature in Kelvin
     virtual void setTemperature(const doublereal temp) {
+        if (temp <= 0) {
+            throw CanteraError("Phase::setTemperature",
+                               "temperature must be positive");
+        }
         m_temp = temp;
     }
     //@}

src/thermo/Phase.cpp

@@ -21,7 +21,7 @@ Phase::Phase() :
     m_xml(new XML_Node("phase")),
     m_id("<phase>"),
     m_name(""),
-    m_temp(0.0),
+    m_temp(0.001),
     m_dens(0.001),
     m_mmw(0.0),
     m_stateNum(-1),
@@ -38,7 +38,7 @@ Phase::Phase(const Phase& right) :
     m_xml(0),
     m_id("<phase>"),
     m_name(""),
-    m_temp(0.0),
+    m_temp(0.001),
     m_dens(0.001),
     m_mmw(0.0),
     m_stateNum(-1),