more efficient use of muladd in evalpoly macro

JuliaLang · Apr 21, 2016 · 413ffc7 · 413ffc7
1 parent 09579e7
commit 413ffc7
Showing 1 changed file with 2 additions and 2 deletions.
diff --git a/base/math.jl b/base/math.jl
@@ -74,15 +74,15 @@ macro evalpoly(z, p...)
         ai = symbol("a", i)
         push!(as, :($ai = $a))
         a = :(muladd(r, $ai, $b))
-        b = :(muladd(-s, $ai, $(esc(p[i]))))
+        b = :($(esc(p[i])) - s * $ai) # don't have efficient multiply-subtract
     end
     ai = :a0
     push!(as, :($ai = $a))
     C = Expr(:block,
              :(x = real(tt)),
              :(y = imag(tt)),
              :(r = x + x),
-             :(s = x*x + y*y),
+             :(s = muladd(x, x, y*y)),
              as...,
              :(muladd($ai, tt, $b)))
     R = Expr(:macrocall, symbol("@horner"), :tt, map(esc, p)...)