Subtracting a value from a vector

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SUMMARY

The discussion centers on the mathematical operation of subtracting a scalar from a vector, specifically the expression z - 1. It is established that mixing a vector and a scalar in subtraction typically lacks meaning unless both are treated as elements of the same dimensional space. In cases where z is a complex number, the scalar 1 can be interpreted as a complex number (1 + 0i), allowing for valid vector operations. The conversation emphasizes the importance of understanding the vector space and scalar field involved in such operations.

PREREQUISITES
  • Understanding of vector spaces and their dimensions
  • Familiarity with complex numbers and their representation
  • Knowledge of vector addition and scalar multiplication rules
  • Concept of isomorphism in mathematical structures
NEXT STEPS
  • Study the properties of one-dimensional vector spaces
  • Learn about complex number operations in vector spaces
  • Explore the concept of isomorphism in linear algebra
  • Investigate formal sums in Graßmann algebra
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Mathematicians, physics students, and anyone studying linear algebra or vector calculus who seeks to understand the implications of operations involving vectors and scalars.

Aristarchus_
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Homework Statement
If we have a vector z, what does it mean to subtract a value of 1 from it? What is the geometric interpretation of this?
Relevant Equations
z-1
d
 
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What are your thoughts so far? Do you think it's okay to mix a vector and a scalar in a subtraction operation like that?
 
Aristarchus_ said:
Homework Statement:: If we have a vector z, what does it mean to subtract a value of 1 from it? What is the geometric interpretation of this?
Relevant Equations:: z-1

d
It generally makes no sense to add a scalar to a vector or to subtract a scalar from a vector. If z happens to be a complex number, then the expression ##z - 1## is treating 1 as also being a complex number (i.e., 1 + 0i), so both z and 1 are essentially vectors.
 
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Aristarchus_ said:
Homework Statement:: If we have a vector z, what does it mean to subtract a value of 1 from it? What is the geometric interpretation of this?
Relevant Equations:: z-1

d
It means that you add two numbers, ##z## and ##1.##

Explanation: You can only add vectors from the same set*). You said that ##z## is a vector. In order to add ##1## to ##z## they have to be of the same dimension*). So ##z+1## demands to be the vector addition in a one-dimensional vector space. Now, a one-dimensional vector space is isomorphic to (~ the same as) the scalar field of the vector space, whatever this is in your case. I assume the real or complex numbers. Therefore ##z+1## is the addition of two numbers, which at the same time are vectors from a one-dimensional vector space.

You see that I already had to make several guesses to answer your question at all! What was missing?
  1. Where is ##z## from? Which vector space?
  2. What scalar field do you have? Means, if you multiply a vector by a number, where is the number from?
  3. What is the dimension of the vector space?
  4. Is it a graduated vector space that allows vectors from different dimensions?
  5. Is ##1## an abbreviation, e.g. ##1=(1,\ldots,1)##?

______________
*) This is not 100% true since we can have formal sums like those in a Graßmann algebra, but as you have to ask this question, I allowed myself to make the assumption of a finite-dimensional vector space of one given dimension.
 

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