# Generating and computing tensor subblocks for mixed spaces

Add functionality for computing only subblocks of the element tensors.

This is useful both for standard mixed spaces and for restricted mixed spaces.

## Blueprint information

- Status:
- Not started

- Approver:
- None

- Priority:
- Low

- Drafter:
- None

- Direction:
- Needs approval

- Assignee:
- None

- Definition:
- Discussion

- Series goal:
- None

- Implementation:
- Unknown

- Milestone target:
- None

- Started by

- Completed by

### Whiteboard

MER: Two design suggestions:

Alternative 1:

--------------

Generate integrals for each "block" and keep track of them in a nested

hierarchy (similar to dofmaps and elements) ala

class *_integral {

virtual ufc::integral* create_

...

}

Alternative 2:

--------------

Add function 'tabulate_

void tabulate_

where block is of length rank and refers to the top level

of the mixed space. For more flexibility, we could

also add:

void tabulate_

for block relative to nestation level.

NB: Important to reuse geometry computations when possible.