I don't think this will work, since `simd_single` and `simd_double` are arrays.

Since you're only ever adding one value to siid_double, you could make them strings instead, which will work:

```ruby
if Hardware.cpu_type == :intel
  simd_single = "--enable-sse"
  simd_double = "--enable-sse2"
elsif Hardware.ppc_family != :g3
  simd_single = "--enable-altivec"
  simd_double = ""
end
```