improve inference in Fun multiplication (#204)

* improve inference in Fun multiplication

* version bump to v0.7.6

* hardcode literal exponents in intpow

Author: jishnub

Project.toml

@@ -1,6 +1,6 @@
 name = "ApproxFunBase"
 uuid = "fbd15aa5-315a-5a7d-a8a4-24992e37be05"
-version = "0.7.5"
+version = "0.7.6"
 
 [deps]
 AbstractFFTs = "621f4979-c628-5d54-868e-fcf4e3e8185c"

src/Fun.jl

@@ -359,8 +359,14 @@ function intpow(f::Fun,k::Integer)
         ones(cfstype(f), space(f))
     elseif k==1
         f
+    elseif k==2
+        f * f
+    elseif k==3
+        f * f * f
+    elseif k==4
+        f * f * f * f
     else
-        t = foldl(*, fill(f, abs(k)))
+        t = foldl(*, fill(f, abs(k)-1), init=f)
         if k > 0
             return t
         else

src/Operators/banded/Multiplication.jl

@@ -146,7 +146,7 @@ end
 
 coefficienttimes(f::Fun,g::Fun) = Multiplication(f,space(g))*g
 
-function transformtimes(f::Fun,g::Fun, n = ncoefficients(f) + ncoefficients(g) - 1, sp = space(f))
+@inline function transformtimes(f::Fun,g::Fun, n = ncoefficients(f) + ncoefficients(g) - 1, sp = space(f))
     @assert pointscompatible(sp,space(g))::Bool
     iszero(ncoefficients(f)) && return f
     iszero(ncoefficients(g)) && return g