From e0b8f424ef9f57b3d50ce30d618109d072dc674c Mon Sep 17 00:00:00 2001
From: Michiel Cottaar <michiel.cottaar@ndcn.ox.ac.uk>
Date: Tue, 30 Jan 2024 16:03:50 +0000
Subject: [PATCH] Avoid divisions in ChangingGradientBlocks
---
src/gradients/changing_gradient_blocks.jl | 6 ++++--
src/gradients/pulsed_gradients.jl | 4 ++--
2 files changed, 6 insertions(+), 4 deletions(-)
diff --git a/src/gradients/changing_gradient_blocks.jl b/src/gradients/changing_gradient_blocks.jl
index 850fe6c..e589c2f 100644
--- a/src/gradients/changing_gradient_blocks.jl
+++ b/src/gradients/changing_gradient_blocks.jl
@@ -8,7 +8,7 @@ import ...BuildingBlocks: GradientBlock, fixed, RFPulseBlock
struct AbstractChangingGradientBlock{T<:VariableType} <: GradientBlock
gradient_strength_start :: SVector{3, T}
- gradient_strength_end :: SVector{3, T}
+ slew_rate :: SVector{3, T}
duration :: T
rotate :: Union{Nothing, Symbol}
scale :: Union{Nothing, Symbol}
@@ -34,7 +34,9 @@ const FixedChangingGradientBlock = AbstractChangingGradientBlock{Float64}
duration(cgb::AbstractChangingGradientBlock) = cgb.duration
-slew_rate(cgb::AbstractChangingGradientBlock) = (cgb.gradient_strength_end .- cgb.gradient_strength_start) ./ duration(cgb)
+grad_start(cgb::AbstractChangingGradientBlock) = cgb.gradient_strength_start
+slew_rate(cgb::AbstractChangingGradientBlock) = cgb.slew_rate
+grad_end(cgb::AbstractChangingGradientBlock) = gradient_strength(cgb) .+ slew_rate(cgb) .* duration(cgb)
gradient_strength(cgb::AbstractChangingGradientBlock) = max.(cgb.gradient_strength_start, cgb.gradient_strength_start)
qvec(cgb::AbstractChangingGradientBlock) = (cgb.gradient_strength_start .+ cgb.gradient_strength_end) .* (duration(cgb)/2)
diff --git a/src/gradients/pulsed_gradients.jl b/src/gradients/pulsed_gradients.jl
index 8897d98..372039b 100644
--- a/src/gradients/pulsed_gradients.jl
+++ b/src/gradients/pulsed_gradients.jl
@@ -85,9 +85,9 @@ function PulsedGradient(model::Model; orientation=nothing, rise_time=nothing, fl
res = PulsedGradient(
model,
- ChangingGradientBlock(zeros(3), grad, rise_time, rotate, scale),
+ ChangingGradientBlock(zeros(3), slew_rate, rise_time, rotate, scale),
ConstantGradientBlock(grad, flat_time, rotate, scale),
- ChangingGradientBlock(grad, zeros(3), rise_time, rotate, scale),
+ ChangingGradientBlock(grad, -slew_rate, rise_time, rotate, scale),
slew_rate,
rate_1d,
rotate,
--
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