Fixing Error in Tag Times: Get Quick Solutions!

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SUMMARY

The discussion addresses an error encountered in Mathematica related to the definition of the variable K. The error message indicates that K has already been defined, and users can resolve this by entering K = . to remove the previous definition. The issue arises from the substitution of K with a mathematical expression that includes variables [q_, N_], which cannot be assigned using the := operator. Understanding the concept of "Tag" and its relation to protected symbols in Mathematica is crucial for troubleshooting this error.

PREREQUISITES
  • Familiarity with Mathematica syntax and operators, particularly :=
  • Understanding of variable definitions and substitutions in Mathematica
  • Knowledge of protected symbols and their implications in Mathematica
  • Basic grasp of mathematical operations and their representation in programming
NEXT STEPS
  • Research how to manage variable definitions in Mathematica effectively
  • Learn about protected symbols in Mathematica and how to work with them
  • Explore the use of the := operator in Mathematica for function definitions
  • Study error handling and debugging techniques in Mathematica
USEFUL FOR

Mathematica users, programmers dealing with variable definitions, and anyone troubleshooting mathematical errors in their scripts.

EdisT
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Hey, I'm unsure why the following returns an error:

1e12560bae48b507c072815f32cb9bbf.png


Any ideas on how to fix this?
 
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It means that you already defined K. Entering K = . will remove the previous definition of K, so you can define it again as a function.
 
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DrClaude said:
It means that you already defined K. Entering K = . will remove the previous definition of K, so you can define it again as a function.
Ah thank you!
 
Not the most helpful error message...
 
Mark44 said:
Not the most helpful error message...
That's because the error occurs after the substitution has been done. If you look carefully,
EdisT said:
1e12560bae48b507c072815f32cb9bbf.png
you will see the presence of [q_, N_] after a bunch of math. That bunch of math is what K was equal to: K[q_, N_] was substituted by <<value of K>>[q_, N_], including some mathematical operations that cannot appear on the left side of := .

It doesn't take long to get acquainted with "Tag [...] is Protected" in Mathematica, and one never forgets what they are due to :smile:
 
I get "Tag" but "Tag Times in ... " is inscrutable. Is "Times" the name of a variable in the OP's script?
 
Mark44 said:
I get "Tag" but "Tag Times in ... " is inscrutable. Is "Times" the name of a variable in the OP's script?
No, it's multiplication (in the core Mathematica language).
 

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