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Martin Ender
Martin Ender
07:42
Say you define one of the unused operators like ±x_ := {x, -x} ... how do I clear that definition? I can't seem to find a related question on main, but it seems like something that would have been asked before.
oh, I just Clear[PlusMinus], don't I? Ignore me...
Kuba
Kuba
07:58
@MartinEnder :)
 
2 hours later…
J. M.
J. M.
10:16
@MartinEnder Can't get simpler than that. :)
 
3 hours later…
Kuba
Kuba
12:51
@J.M. 7 so far: meta.mathematica.stackexchange.com/q/1881/5478
J. M.
J. M.
13:02
@Kuba The first upvote was mine; nevertheless, do add more examples if you come across them while there are no other tag name proposals.
Shutao TANG
Shutao TANG
Hello, everyone! I would like to know: is there good method to achive the following functionality?
Kuba
Kuba
@J.M. sure, thanks.
Shutao TANG
Shutao TANG
user image
I mainly use RepacePart[]
elemAdjust[elems_, deg_, i_] :=
Module[{idx, n = Length[elems] - 1, new},
idx = Select[{i - deg - 1, i, i + deg + 1}, 0 <= # <= n &] + 1;
new = Transpose@ConstantArray[elems[[idx]], 2];
Flatten[ReplacePart[elems, Thread[idx -> new]], 1]
]
Meta
Meta
1
Q: Extending built in functionalities tag

KubaWhile we have customization tag I think it would be nice to have more localized one which would group questions like: How to implement custom integration rules for use by NIntegrate How to create custom Graphics primitive? Is it possible to define a new PlotTheme? Is it possible to insert new c...

discussion tagging
Shutao TANG
Shutao TANG
pts = {P0, P1, P2, P3, P4, P5, P6, P7};
elemAdjust[pts, 2, 1]
elemAdjust[pts, 2, 3]
J. M.
J. M.
13:12
Try Flatten[Partition[Array[C, 8, 0], 4, 3, {3, -3}, {}]] for the first, and Flatten[Partition[Array[C, 8, 0], 4, 3, {-1, 1}, {}]] for the second.
Shutao TANG
Shutao TANG
@J.M. Thanks:) Is it a general solution to this problem?
J. M.
J. M.
@ShutaoTANG Well, you'll need to ponder on how to use the second, third, and fourth arguments of Partition[] for this.
Shutao TANG
Shutao TANG
@J.M. Yes, to be honest, I didn't master the other usage of Partition[] apart from basic usage. In addtion, could you know how to calculate the complement of two sets? Like this?
knotsCommon = {0, 0, 0, 0, 0.25, 0.25, 1, 1, 1, 1};
knots1 = {0, 0, 0, 0, 0.25, 1, 1, 1, 1};
Complement[knotsCommon, knots1]
which returns {}, but I hope the result should be {0.25}
J. M.
J. M.
@ShutaoTANG but 0.25 is in both lists; what were you expecting from Complement[]?
Shutao TANG
Shutao TANG
13:28
@J.M. Now I know Complement[] will delete the duplicate element. In fact, I would like to use knotsCommon minus knots1, then returning the remaining element, like 0.25
J. M.
J. M.
@ShutaoTANG That's not how set complement works. As said in the docs, the result is a list of everything in the first list that is not in the second and subsequent lists. But, the numbers in your knots1 are all in knotsCommon!
Shutao TANG
Shutao TANG
14:25
@J.M. The problem comes from the B-spline degree elevate. Here is a example
point = {{0, 0}, {4, 4}, {20, 12}, {32, 0}};
knots = {0, 0, 0, 0.25, 1, 1, 1};

pointElevate = {{0, 0}, {8/3, 8/3}, {16/3, 14/3}, {16., 10.}, {24, 8}, {32, 0}};
knotsElevate = {0, 0, 0, 0, 0.25, 0.25, 1, 1, 1, 1};
Graphics[{Opacity[0.5], Red,
BSplineCurve[point, SplineDegree -> 2, SplineKnots -> knots], Blue,
Dashed, BSplineCurve[pointElevate, SplineDegree -> 3,
SplineKnots -> knotsElevate]}]
 
2 hours later…
Pickett
Pickett
16:12
@ShutaoTANG Something like Fold[# /. {a___, #2, b___} :> {a, b} &, knotsCommon, knots1]?
Szabolcs
Szabolcs
16:24
Can anyone comment on this?
1
Q: Checking inequalities: How can $x>0,y>0$ yet $x+y$ indeterminate?

U.T.I have the following: $Assumptions = {0 < Ijm1 < Ij < Ijp1 < 1, bpjm1 < 0, bpj < 0, bpjp1 < 0, Ijm1 \[Element] Reals, Ij \[Element] Reals, Ijp1 \[Element] Reals, bpjm1 \[Element] Reals, bjp \[Element] Reals, bpjp1 \[Element] Reals}; x = (1 - bpjp1 Ijp1 + bpjp1 Ijp1^2) ; y = bpj (Ij - Ijm1) (-...

simplifying-expressions inequalities
Sjoerd C. de Vries
Sjoerd C. de Vries
16:45
@VitaliyKaurov I have added better (IMHO) code to that post...
 
2 hours later…
Szabolcs
Szabolcs
18:17
So this got reopened:
24
Q: Are you interested in a Wolfram Workbench Update?

Frank MartinI also posted this on the Wolfram Community site (link below) Last week I attended the Wolfram Tour (which was great). I asked whenever we could expect a new version of Workbench, as the current (public) version 2 is very out dated. They responded that they use a more up to date version internal...

documentation workbench
Is there a good reasoning behind reopening? Wouldn't it be better on meta if we keep it?
It's not that it isn't worth having a discussion on this topic, but this post is just so far from a "practical, answerable question". It simply doesn't fit SE. It would fit meta.
 
3 hours later…
Kuba
Kuba
21:24
@Szabolcs doesn't really matter for me where it is, I think it doesn't fit both. I'd even say it fits better here than meta. (I didn't vote to reopen {unless I missclicked in review})
on-topic in meta seems to be only about mma.se site so I don't know.
Sascha
Sascha
21:43
user image
@Kuba This is what my question was about. Do you think this would be helpful to other people struggling with the second argument to Dynamic. If so I would post my code as an answer

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