Remove _condition_number and replace by LinearAlgebra.cond (#208)

* Remove `_condition_number` and replace by `LinearAlgebra.cond`

* Bump TensorKit version to 0.14.6

Author: pbrehmer

Project.toml

@@ -41,7 +41,7 @@ Printf = "1"
 QuadGK = "2.11.1"
 Random = "1"
 Statistics = "1"
-TensorKit = "0.14"
+TensorKit = "0.14.6"
 TensorOperations = "5"
 VectorInterface = "0.4, 0.5"
 Zygote = "0.6, 0.7"

src/utility/svd.jl

@@ -146,13 +146,6 @@ end
 
 ## Forward algorithms
 
-# Compute condition number smax / smin for diagonal singular value TensorMap
-function _condition_number(S::AbstractTensorMap)
-    smax = maximum(first ∘ last, blocks(S))
-    smin = maximum(last ∘ last, blocks(S))
-    return smax / smin
-end
-
 # Copy code from TensorKit but additionally return full U, S and V to make compatible with :fixed mode
 function _tsvd!(
     t::TensorMap{<:RealOrComplexFloat},
@@ -176,7 +169,7 @@ function _tsvd!(
     end
 
     # construct info NamedTuple
-    condnum = _condition_number(S)
+    condnum = cond(S)
     info = (;
         truncation_error=truncerr, condition_number=condnum, U_full=U, S_full=S, V_full=V⁺
     )
@@ -217,7 +210,7 @@ end
 function _tsvd!(_, alg::FixedSVD, ::TruncationScheme, ::Real)
     info = (;
         truncation_error=0,
-        condition_number=_condition_number(alg.S),
+        condition_number=cond(alg.S),
         U_full=alg.U_full,
         S_full=alg.S_full,
         V_full=alg.V_full,
@@ -272,7 +265,7 @@ function _tsvd!(f, alg::IterSVD, trunc::TruncationScheme, p::Real)
         trunc isa NoTruncation ? abs(zero(scalartype(f))) : norm(U * S * V - f, p)
 
     # construct info NamedTuple
-    condition_number = _condition_number(S)
+    condition_number = cond(S)
     info = (;
         truncation_error, condition_number, U_full=nothing, S_full=nothing, V_full=nothing
     )