3
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I've reduced some of my code to the code here

Manipulate[
(*output here here*)
{j, 1, 40, 1},
{k, 1, Dynamic[j], 1},
]

The problem I'd like to fix is that if I set j to 40, then k to 35, and then set j down to 20, a bunch of errors get thrown. Is there a way to add something to the code here that when j gets updated k gets reset to 1?

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2
  • $\begingroup$ try replacing {j, 1, 40, 1} with {j, 1, 40, 1, TrackingFunction -> (j = #; k = 1; &)}? $\endgroup$
    – kglr
    Commented Jan 30 at 7:08
  • 1
    $\begingroup$ .. or with {j, 1, 40, 1, TrackingFunction -> (j = #; k = Min[#, k]; &)} to reset k to j when j moves below current value of k (as in Nasser's answer). $\endgroup$
    – kglr
    Commented Jan 30 at 7:42

2 Answers 2

Reset to default
3
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I assume by error, you mean you get this red marking.

enter image description here

This just says upper limit of slider is reached. You can throttle this like this

Manipulate[
 If[k > j, k = j];
 Row[{"j=", j, ", k=", k}],
 {{j, 1, "j"}, 1, 40, 1, Appearance -> "Labeled"},
 {{k, 1, "k"}, 1, Dynamic[j], 1, Appearance -> "Labeled"},
 TrackedSymbols :> {j, k}
 ]

And now if upper limit for k is more than j, it will go to match j.

You should also always add TrackedSymbols

enter image description here

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2
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Using an explicit Dynamic is not necessary.

$Version

(* "14.0.0 for Mac OS X ARM (64-bit) (December 13, 2023)" *)

Clear["Global`*"]

Manipulate[
 k = Min[k, j];
 StringForm["j = ``; k = ``", j, k],
 {{j, 20}, 1, 40, 1, Appearance -> "Labeled"},
 {{k, 10}, 1, j, 1, Appearance -> "Labeled"},
 SynchronousUpdating -> False,
 TrackedSymbols :> {j, k}]
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