Merge #125

125: Try replacing pow with exp log r=charleskawczynski a=charleskawczynski I may try to add Float32 perf tests, just to see / verify from here that this is problematic. Co-authored-by: Charles Kawczynski <[email protected]>
CliMA · Aug 17, 2022 · 2a8aa23 · 2a8aa23 · charleskawczynski · Aug 17, 2022
2 parents e39a650 + caea43f
commit 2a8aa23
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Showing 2 changed files with 7 additions and 2 deletions.
diff --git a/Project.toml b/Project.toml
@@ -1,7 +1,7 @@
 name = "Thermodynamics"
 uuid = "b60c26fb-14c3-4610-9d3e-2d17fe7ff00c"
 authors = ["Climate Modeling Alliance"]
-version = "0.9.3"
+version = "0.9.4"
 
 [deps]
 DocStringExtensions = "ffbed154-4ef7-542d-bbb7-c09d3a79fcae"

diff --git a/src/relations.jl b/src/relations.jl
@@ -923,6 +923,10 @@ function saturation_vapor_pressure(
     return saturation_vapor_pressure(param_set, T, LH_0, Δcp)
 end
 
+# we may be hitting a slow path:
+# https://stackoverflow.com/questions/14687665/very-slow-stdpow-for-bases-very-close-to-1
+pow_hack(x, y) = exp(y * log(x))
+
 function saturation_vapor_pressure(
     param_set::APS,
     T::FT,
@@ -935,7 +939,8 @@ function saturation_vapor_pressure(
     T_0::FT = TP.T_0(param_set)
 
     return press_triple *
-           (T / T_triple)^(Δcp / R_v) *
+           # (T / T_triple)^(Δcp / R_v) *
+           pow_hack(T / T_triple, Δcp / R_v) *
            exp((LH_0 - Δcp * T_0) / R_v * (1 / T_triple - 1 / T))
 
 end