Support for mlx.float64

[kyrollosyanny]

Describe the bug
Would it be possible to support float64 types. For some numerical simulations, having float64 is important for the accuracy of the simulation. The goal is to use mlx for automatic differentiation in these types of scenarios.

[awni]

Double isn’t possible in Metal. In theory we could do it on the CPU only, but that is likely a lot less interesting to you?

[kyrollosyanny]

For some simulations and optimizations, cpu is more than enough. If it is possible to add that support in future versions, that would be great. Thanks a lot.

[awni]

Sounds good, I'll leave this open for now as a possible enhancement. I don't know if we will do it, but people can comment here with use cases etc to help us prioritize.

[Andyuch]

It would be so grateful and helpful if the float64 will be added, there is a similar issue appearing in my scientific simulation using 'mps' in pytorch.