taichi-dev/taichi

[Lang] Python-scope matrix/vector operations

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#1,008 opened on May 17, 2020

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 (7 comments) (1 reaction) (1 assignee)C++ (28,195 stars) (2,384 forks)batch import
feature requestgood first issuewelcome contribution

Description

Concisely describe the proposed feature Currently, the Matrix class operations (e.g. matrix add/multiply/scale) can happen only in Taichi kernels. In some cases having these work in Python-scope is necessary. For example, https://github.com/taichi-dev/taichi/pull/1006/files#diff-9ce279666131a93e7f2be366688b2fa1R52-R67

Without Python-scope matrix operation supports users have to fall back on numpy and the conversion between Taichi and numpy can be troublesome.

Describe the solution you'd like (if any) Dispatch matrix operations according to the scope. Keep the old behavior if the operation happens in Taichi-scope, but evaluate the results immediately in Python-scope.

To decide the scope, use ti.get_runtime().inside_kernel. E.g.,

https://github.com/taichi-dev/taichi/blob/6dce0c4bceafcbf8347684802ef29c9fb84266d7/python/taichi/lang/expr.py#L143

Contributor guide

Tech stack
pythoncpp
Domain
backend
Issue type
feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
blocked
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
Basic knowledge of Taichi kernel systemFamiliarity with matrix operations
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
40
Research direction
The issue requests adding Python scope matrix/vector operations to Taichi. The solution is to dispatch matrix operations based on scope using `ti.get runtime().inside kernel`, as shown in the existing code in `python/taichi/lang/expr.py`. Examine the linked PR #1006 for context on where the fallback to numpy is required. Implement evaluation immediately in Python scope while retaining Taichi scope behavior.