Fix bug with sorting eigenvectors in eps_non_dc; update docstring

- Calling sort on the eigenvalues from eigen() for an
  MT{<:Measurements.Measurement} led to an error.  Remove the call
  to sort() since eigen() by default sorts the eigenvalues in
  ascending order.
- Update the docstring for decompose() to reflect the actual output.

Project.toml

@@ -1,7 +1,7 @@
 name = "MomentTensors"
 uuid = "7bb32750-d21c-11e8-1ebc-09158bc70490"
 authors = ["Andy Nowacki <a.nowacki@leeds.ac.uk>"]
-version = "0.2.3"
+version = "0.2.4"
 
 [compat]
 julia = "0.7, 1"

src/MomentTensors.jl

@@ -399,7 +399,8 @@ where the eigenvalues of the moment tensor are λ₁ ≥ λ₂ ≥ λ₃.
   Observation North-Holland, Amsterdam, Theory and Interpretation, pp. 345-353.
 """
 function eps_non_dc(m::MT)
-    λ = sort(eigen(Symmetric(_matrix(m))).values)
+    # eigen returns eigenvalues sorted by default
+    λ = eigen(Symmetric(_matrix(m))).values
     -λ[2]/max(abs(λ[1]), abs(λ[3]))
 end
 
@@ -446,11 +447,14 @@ struct MTDecomposition{T<:Number}
 end
 
 """
-    decompose(m::MT) -> m_iso, m_dev, m_dc, m_clvd
+    decompose(m::MT) -> iso, dev, dc, clvd, m0_iso, m0_dev, prop_iso, prop_dev, prop_dc, prop_clvd, m0
 
-Decompose the arbitrary moment tensor `m` into its isotropic, `m_iso`,
-and deviatoric parts, `m_dev`, plus the CLVD, `m_clvd`, and double-couple,
-`m_dc`, components
+Decompose the arbitrary moment tensor `m` into its isotropic, `iso`,
+and deviatoric parts, `dev`, plus the CLVD, `clvd`, and double-couple,
+`dc`, components.  The proportion of the moment tensor represented by
+the isotropic, deviatoric, double-couple and CLVD components are
+given respectively by `prop_iso`, `prop_dev`, `prop_dc` and `prop_clvd`.
+The scalar moment in Nm is given by `m0`.
 """
 function decompose(m::MT{T}) where T
     tr = m[1] + m[2] + m[3]

test/decompose.jl

@@ -22,5 +22,6 @@ using MomentTensors, Test
         @test d.prop_clvd ≈ 0.32 atol=0.01
         @test d.m0 ≈ 14.9031089939
         @test mw(d.m0) ≈ -5.25114874821
+        @test eps_non_dc(m) ≈ -0.34250995536253115
     end
 end