multi-gradient implementation
- Concern : API/UI/Documentation
- Platform : macOS/Linux/Windows
- Version of the software: v3.6.3
- Problem description : The drawing and implementation of the multigradient array presented in the forward model tab is inconsistent.
What we have in the forward model tab:

@jamyd91 in the function (seqGen.py), there are several parameters used, a, n, m but also an si parameter. Can you clarify this?
