Why Doesn't Chop[] Remove I.0 from the Output?

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Discussion Overview

The discussion revolves around the use of the Chop[] function in Mathematica and its effectiveness in removing the term I.0 from an output expression. Participants explore the implications of using Chop[], the nature of the input that generates the output, and the mathematical operations involved, particularly focusing on dot products and conjugates.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant reports that using Chop[] does not remove I.0 from their output, despite suggestions from various sources.
  • Another participant suggests that Conjugate'[] appears to be the derivative of the conjugate function, referencing an external source for clarification.
  • A request for a screenshot of the output is made to better understand the issue at hand.
  • Participants inquire about the specific input that generated the problematic output.
  • One participant proposes that to eliminate I.0 from the output, it should be removed from the input, suggesting that having a dot product of two scalars is nonsensical and may indicate an error in the code.
  • A later reply indicates that the issue has been resolved by the original poster, who acknowledges an error in their code related to the dimensions of matrices involved in the dot product.
  • Another participant expresses skepticism about the validity of a dot product involving I, noting that the documentation for Dot suggests that if the arguments are not lists, the operation remains unevaluated, which aligns with the observed behavior.

Areas of Agreement / Disagreement

Participants express differing views on the appropriateness of the dot product involving I and the implications of using Chop[]. While some suggest that the issue is rooted in the input, others focus on the behavior of the Dot function. The discussion remains unresolved regarding the best approach to handle the output and the implications of the mathematical operations involved.

Contextual Notes

Participants note that the behavior of the Dot function may depend on the types and dimensions of the inputs, which could lead to different outcomes based on how the inputs are structured.

Natthawin Cho
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As I found on many websites, they suggest to use Chop[]. I tried that already but it doesn't work.

This is my output.

{{2 (Conjugate[
I.0] I.0 + (Conjugate[I.0] + Conjugate[Subscript[v, 1]]/Sqrt[
2]) (I.0 + Subscript[v, 1]/Sqrt[2])) Subscript[\[Lambda],
1] (Conjugate[I.0] + Conjugate[Subscript[v, 1]]/Sqrt[
2] + (I.0 + Subscript[v, 1]/Sqrt[2]) Derivative[1][Conjugate][
I.0 + Subscript[v, 1]/Sqrt[2]]) + (Conjugate[
I.0] I.0 + (Conjugate[I.0] + Conjugate[Subscript[v, 2]]/Sqrt[
2]) (I.0 + Subscript[v, 2]/Sqrt[2])) Subscript[\[Lambda],
5] (Conjugate[I.0] + Conjugate[Subscript[v, 1]]/Sqrt[
2] + (I.0 + Subscript[v, 1]/Sqrt[2]) Derivative[1][Conjugate][
I.0 + Subscript[v, 1]/Sqrt[2]]) +
1/2 (2 Conjugate[
I.0] I.0 + (Conjugate[I.0] + Conjugate[Subscript[v, 2]]/Sqrt[
2]) (I.0 + Subscript[v, 1]/Sqrt[2]) + (Conjugate[I.0] +
Conjugate[Subscript[v, 1]]/Sqrt[2]) (I.0 + Subscript[v, 2]/
Sqrt[2])) Subscript[\[Lambda],
6] (Conjugate[I.0] + Conjugate[Subscript[v, 1]]/Sqrt[
2] + (I.0 + Subscript[v, 1]/Sqrt[2]) Derivative[1][Conjugate][
I.0 + Subscript[v, 1]/Sqrt[2]]) -
1/2 I (-(Conjugate[I.0] + Conjugate[Subscript[v, 2]]/Sqrt[
2]) (I.0 + Subscript[v, 1]/Sqrt[2]) + (Conjugate[I.0] +
Conjugate[Subscript[v, 1]]/Sqrt[2]) (I.0 + Subscript[v, 2]/
Sqrt[2])) Subscript[\[Lambda],
8] (Conjugate[I.0] + Conjugate[Subscript[v, 1]]/Sqrt[
2] + (I.0 + Subscript[v, 1]/Sqrt[2]) Derivative[1][Conjugate][
I.0 + Subscript[v, 1]/Sqrt[2]]) - \!\(
\*SubsuperscriptBox[\(\[Mu]\), \(1\), \(2\)]\ \((Conjugate[I . 0] +
\*FractionBox[\(Conjugate[
\*SubscriptBox[\(v\), \(1\)]]\),
SqrtBox[\(2\)]] + \((I . 0 +
\*FractionBox[
SubscriptBox[\(v\), \(1\)],
SqrtBox[\(2\)]])\)\ \*
SuperscriptBox["Conjugate", "\[Prime]",
MultilineFunction->None][I . 0 +
\*FractionBox[
SubscriptBox[\(v\), \(1\)],
SqrtBox[\(2\)]]])\)\) -
1/2 (-(Conjugate[I.0] + Conjugate[Subscript[v, 2]]/Sqrt[2]) (I.0 +
Subscript[v, 1]/Sqrt[2]) + (Conjugate[I.0] +
Conjugate[Subscript[v, 1]]/Sqrt[2]) (I.0 + Subscript[v, 2]/
Sqrt[2])) Subscript[\[Lambda],
4] (-Conjugate[I.0] - Conjugate[Subscript[v, 2]]/Sqrt[
2] + (I.0 + Subscript[v, 2]/Sqrt[2]) Derivative[1][Conjugate][
I.0 + Subscript[v, 1]/Sqrt[2]]) -
1/2 I (Conjugate[
I.0] I.0 + (Conjugate[I.0] + Conjugate[Subscript[v, 1]]/Sqrt[
2]) (I.0 + Subscript[v, 1]/Sqrt[2])) Subscript[\[Lambda],
8] (-Conjugate[I.0] - Conjugate[Subscript[v, 2]]/Sqrt[
2] + (I.0 + Subscript[v, 2]/Sqrt[2]) Derivative[1][Conjugate][
I.0 + Subscript[v, 1]/Sqrt[2]]) -
1/2 I (Conjugate[
I.0] I.0 + (Conjugate[I.0] + Conjugate[Subscript[v, 2]]/Sqrt[
2]) (I.0 + Subscript[v, 2]/Sqrt[2])) Subscript[\[Lambda],
9] (-Conjugate[I.0] - Conjugate[Subscript[v, 2]]/Sqrt[
2] + (I.0 + Subscript[v, 2]/Sqrt[2]) Derivative[1][Conjugate][
I.0 + Subscript[v, 1]/Sqrt[2]]) -
1/4 I (2 Conjugate[
I.0] I.0 + (Conjugate[I.0] + Conjugate[Subscript[v, 2]]/Sqrt[
2]) (I.0 + Subscript[v, 1]/Sqrt[2]) + (Conjugate[I.0] +
Conjugate[Subscript[v, 1]]/Sqrt[2]) (I.0 + Subscript[v, 2]/
Sqrt[2])) Subscript[\[Lambda],
10] (-Conjugate[I.0] - Conjugate[Subscript[v, 2]]/Sqrt[
2] + (I.0 + Subscript[v, 2]/Sqrt[2]) Derivative[1][Conjugate][
I.0 + Subscript[v, 1]/Sqrt[2]]) + 1/2 I
\!\(\*SubsuperscriptBox[\(\[Mu]\), \(4\), \(2\)]\) (-Conjugate[I.0] -
Conjugate[Subscript[v, 2]]/Sqrt[
2] + (I.0 + Subscript[v, 2]/Sqrt[2]) Derivative[1][Conjugate][
I.0 + Subscript[v, 1]/Sqrt[2]]) +
1/2 (2 Conjugate[
I.0] I.0 + (Conjugate[I.0] + Conjugate[Subscript[v, 2]]/Sqrt[
2]) (I.0 + Subscript[v, 1]/Sqrt[2]) + (Conjugate[I.0] +
Conjugate[Subscript[v, 1]]/Sqrt[2]) (I.0 + Subscript[v, 2]/
Sqrt[2])) Subscript[\[Lambda],
3] (Conjugate[I.0] + Conjugate[Subscript[v, 2]]/Sqrt[
2] + (I.0 + Subscript[v, 2]/Sqrt[2]) Derivative[1][Conjugate][
I.0 + Subscript[v, 1]/Sqrt[2]]) +
1/2 (Conjugate[
I.0] I.0 + (Conjugate[I.0] + Conjugate[Subscript[v, 1]]/Sqrt[
2]) (I.0 + Subscript[v, 1]/Sqrt[2])) Subscript[\[Lambda],
6] (Conjugate[I.0] + Conjugate[Subscript[v, 2]]/Sqrt[
2] + (I.0 + Subscript[v, 2]/Sqrt[2]) Derivative[1][Conjugate][
I.0 + Subscript[v, 1]/Sqrt[2]]) +
1/2 (Conjugate[
I.0] I.0 + (Conjugate[I.0] + Conjugate[Subscript[v, 2]]/Sqrt[
2]) (I.0 + Subscript[v, 2]/Sqrt[2])) Subscript[\[Lambda],
7] (Conjugate[I.0] + Conjugate[Subscript[v, 2]]/Sqrt[
2] + (I.0 + Subscript[v, 2]/Sqrt[2]) Derivative[1][Conjugate][
I.0 + Subscript[v, 1]/Sqrt[2]]) -
1/4 I (-(Conjugate[I.0] + Conjugate[Subscript[v, 2]]/Sqrt[
2]) (I.0 + Subscript[v, 1]/Sqrt[2]) + (Conjugate[I.0] +
Conjugate[Subscript[v, 1]]/Sqrt[2]) (I.0 + Subscript[v, 2]/
Sqrt[2])) Subscript[\[Lambda],
10] (Conjugate[I.0] + Conjugate[Subscript[v, 2]]/Sqrt[
2] + (I.0 + Subscript[v, 2]/Sqrt[2]) Derivative[1][Conjugate][
I.0 + Subscript[v, 1]/Sqrt[2]]) - 1/2
\!\(\*SubsuperscriptBox[\(\[Mu]\), \(3\), \(2\)]\) (Conjugate[I.0] +
Conjugate[Subscript[v, 2]]/Sqrt[
2] + (I.0 + Subscript[v, 2]/Sqrt[2]) Derivative[1][Conjugate][
I.0 + Subscript[v, 1]/Sqrt[2]])}}

I also would like to know the difference between Conjugate[] and Conjugate'[].
 
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This is the screenshot.
cats.jpg
 
What is the input that gave you this?
 
To remove I.0 from your output you should probably remove it from your input. It doesn't make sense to take the dot product of two scalars. I think it indicates an error in your code.
 
I solved that problem already. The error is in my code. I used I dot with matrix. However, I have 1x2 matrix times 2x1 matrix and I get 1x1 matrix. Can I change this to scalar?
 
To me it doesn't make sense to have a dot product of I with anything.

If you read the documentation on Dot it says that if either of the arguments are not lists then the Dot remains unevaluated. So that is consistent with the behavior that we see.
 
Last edited:

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