From 5a376c1669b1007858c806722da86c5233fd7633 Mon Sep 17 00:00:00 2001
From: Michiel Cottaar <michiel.cottaar@ndcn.ox.ac.uk>
Date: Sun, 28 Jan 2024 21:06:22 +0000
Subject: [PATCH] Update instant gradients
---
src/gradients/instant_gradients.jl | 58 +++++++++++++++++++++++-------
1 file changed, 46 insertions(+), 12 deletions(-)
diff --git a/src/gradients/instant_gradients.jl b/src/gradients/instant_gradients.jl
index 435a633..58c96bb 100644
--- a/src/gradients/instant_gradients.jl
+++ b/src/gradients/instant_gradients.jl
@@ -1,42 +1,76 @@
module InstantGradients
-import JuMP: @constraint, @variable, Model, owner_model
-import ...Variables: qval, bval, start_time, duration, variables, get_free_variable, VariableType
+import JuMP: @constraint, @variable, Model, owner_model, AbstractJuMPScalar
+import ...Variables: qvec, bmat, duration, variables, get_free_variable, VariableType
import ...BuildingBlocks: GradientBlock, fixed
import ...BuildSequences: @global_model_constructor
import ..FixedGradients: FixedInstantGradient
"""
- InstantGradientBlock(; orientation=:bvec, qval=nothing)
+ InstantGradientBlock(; orientation=nothing, qval=nothing, qvec=nothing, rotate=nothing, scale=nothing)
Defines an instantaneous gradient.
## Parameters
-- `orientation` sets the gradient orienation. Can be set to a vector for a fixed orientation. Alternatively, can be set to :bvec (default) to rotate with the user-provided `bvecs` or to :neg_bvec to always be the reverse of the `bvecs`.
+- `orientation` sets the gradient orienation (ignored if `qvec` is set). Can be set to a vector for a fixed orientation. Otherwise the orientation will be aligned with the `rotate` (if set) or fully free (if `rotate` is nothing).
+- `rotate`: with which user-set parameter will this gradient be rotated (e.g., :bvec). Default is no rotation.
+- `scale`: with which user-set parameter will this gradient be scaled (e.g., :bval). Default is no scaling.
## Variables
+- [`qvec`](@ref): Spatial scale and direction on which spins will be dephased due to this pulsed gradient in rad/um.
- [`qval`](@ref): Spatial scale on which spins will be dephased due to this pulsed gradient in rad/um.
"""
struct InstantGradientBlock <: GradientBlock
model::Model
- orientation :: Any
- qval :: VariableType
+ qvec :: SVector{3, VariableType}
+ rotate :: Union{Nothing, Symbol}
+ scale :: Union{Nothing, Symbol}
end
@global_model_constructor InstantGradientBlock
-function InstantGradientBlock(model::Model; orientation=:bvec, qval=nothing)
+function InstantGradientBlock(model::Model; orientation=nothing, qval=nothing, qvec=nothing, rotate=nothing, scale=nothing)
+ used_qval = false
+ if isnothing(qvec)
+ if isnothing(orientation)
+ if isnothing(rotate)
+ qvec = SVector{3}(
+ get_free_variable(nothing),
+ get_free_variable(nothing),
+ get_free_variable(nothing),
+ )
+ else
+ qvec = SVector{3}(
+ get_free_variable(qval),
+ 0.,
+ 0.,
+ )
+ used_qval = true
+ end
+ else
+ qval = get_free_variable(qval)
+ qvec = (orientation ./ norm(orientation)) * qval
+ used_qval = true
+ end
+ end
+
res = InstantGradientBlock(
model,
- orientation,
- get_free_variable(model, qval),
+ qvec,
+ rotate,
+ scale
)
- @constraint model model.qval >= 0
+ if !used_qval && !isnothing(qval)
+ @constraint model qval_sqr(res) == qval^2
+ end
+ if qval isa AbstractJuMPScalar
+ @constraint model qval >= 0
+ end
return res
end
-qval(instant::InstantGradientBlock) = instant.qval
-bval(instant::InstantGradientBlock) = 0.
+qvec(instant::InstantGradientBlock) = instant.qvec
+bmat(instant::InstantGradientBlock, qstart=nothing) = zeros(3, 3)
duration(instant::InstantGradientBlock) = 0.
variables(::Type{<:InstantGradientBlock}) = [qval]
--
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