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in vector field feature exraction 
in vector field feature exraction 
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Related to this and possibly simpler: 
Related to this and possibly simpler: 
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image(2)[2] Vimg = load(...); 
image(2)[2] Vimg = load(...); 
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field#1(2)[] Vlen = Vimg ⊛ ctmr; 
field#0(2)[] Vlen = Vimg ⊛ bspln3; 
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to get a scalar field of vector length, or 
to get a scalar field of vector length, or 
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field#1(2)[] F = Fimg ⊛ ctmr; 
field#2(2)[] F = Fimg ⊛ bspln3; 
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field#1(2)[] Gmag = ∇F; 
field#0(2)[] Gmag = ∇F; 
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to get a scalar field of gradient magnitude, or 
to get a scalar field of gradient magnitude, or 
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field#1(2)[] F = Fimg ⊛ ctmr; 
field#2(2)[] F = Fimg ⊛ bspln3; 
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field#1(2)[] Gmsq = ∇F•∇F; 
field#0(2)[] Gmsq = ∇F•∇F; 
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to get a scalar field of squared gradient magnitude 
to get a scalar field of squared gradient magnitude, which is simpler 
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(which is simpler to differentiate) 
to differentiate. Again, though, it would be such a benefit to have 
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these expressions, without any differentiability. Hence my indication 
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of "field#0" for these above. 
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ability to declare a field in such a way so that probe 
ability to declare a field in such a way so that probe 
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positions are *always* clamped to the support of "inside"; 
positions are *always* clamped to the support of "inside"; 