use sum(abs2()) instead of dot

Author: bayesthm

src/pdmat.jl

@@ -68,15 +68,8 @@ end
 
 ### quadratic forms
 
-function quad(a::PDMat, x::AbstractVector)
-    z = a.chol.U * x
-    dot(z, z)
-end
-
-function invquad(a::PDMat, x::AbstractVector)
-    z = a.chol.L \ x
-    dot(z, z)
-end
+quad(a::PDMat, x::AbstractVector) = sum(abs2, a.chol.U * x)
+invquad(a::PDMat, x::AbstractVector) = sum(abs2, a.chol.L \ x)
 
 """
     quad!(r::AbstractArray, a::AbstractPDMat, x::StridedMatrix)