Merge pull request JuliaLang#12935 from stevengj/generic_vecnorm_test

fixed bug and added test for generic vecnorm of array of arrays
laurentbartholdi · Sep 4, 2015 · a4a321a · a4a321a
2 parents cd87abb + 95f3015
commit a4a321a
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Showing 2 changed files with 17 additions and 5 deletions.
diff --git a/base/linalg/generic.jl b/base/linalg/generic.jl
@@ -107,24 +107,29 @@ function generic_vecnorm1(x)
     return convert(T, sum)
 end
 
+# faster computation of norm(x)^2, avoiding overflow for integers
+norm_sqr(x) = norm(x)^2
+norm_sqr(x::Number) = abs2(x)
+norm_sqr{T<:Integer}(x::Union{T,Complex{T},Rational{T}}) = abs2(float(x))
+
 function generic_vecnorm2(x)
     maxabs = vecnormInf(x)
     (maxabs == 0 || isinf(maxabs)) && return maxabs
     s = start(x)
     (v, s) = next(x, s)
     T = typeof(maxabs)
     if isfinite(length(x)*maxabs*maxabs) && maxabs*maxabs != 0 # Scaling not necessary
-        sum::promote_type(Float64, T) = abs2(norm(v)/norm(one(v)))
+        sum::promote_type(Float64, T) = norm_sqr(v)
         while !done(x, s)
             (v, s) = next(x, s)
-            sum += abs2(norm(v)/norm(one(v)))
+            sum += norm_sqr(v)
         end
         return convert(T, sqrt(sum))
     else
         sum = abs2(norm(v)/maxabs)
         while !done(x, s)
             (v, s) = next(x, s)
-            sum += abs2(norm(v)/maxabs)
+            sum += (norm(v)/maxabs)^2
         end
         return convert(T, maxabs*sqrt(sum))
     end
@@ -144,10 +149,10 @@ function generic_vecnormp(x, p)
     end
     spp::promote_type(Float64, T) = p
     if -1 <= p <= 1 || (isfinite(length(x)*maxabs^spp) && maxabs^spp != 0) # scaling not necessary
-        sum::promote_type(Float64, T) = (norm(v)/norm(one(v)))^spp
+        sum::promote_type(Float64, T) = norm(v)^spp
         while !done(x, s)
             (v, s) = next(x, s)
-            sum += (norm(v)/norm(one(v)))^spp
+            sum += norm(v)^spp
         end
         return convert(T, sum^inv(spp))
     else # rescaling

diff --git a/test/linalg/generic.jl b/test/linalg/generic.jl
@@ -124,3 +124,10 @@ end
 
 @test norm([2.4e-322, 4.4e-323]) ≈ 2.47e-322
 @test norm([2.4e-322, 4.4e-323], 3) ≈ 2.4e-322
+
+# test generic vecnorm for arrays of arrays
+let x = Vector{Int}[[1,2], [3,4]]
+    @test norm(x) ≈ sqrt(30)
+    @test norm(x, 1) ≈ sqrt(5) + 5
+    @test norm(x, 3) ≈ cbrt(sqrt(125)+125)
+end