Defining Mathcad Variables to be equal to Unity

In summary, to define a constraint in Mathcad, one must write it as an equation equal to 0 and add it to the list of constraints for the problem.
  • #1
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While attempting to solve quadratic equation application in MATHCAD (pertaining to the Markowitz Portfolio theory), I am now stumped at how to perfom what would seem to be a trivial operation, namely: setting a sum of unknown variables (i.e., a constraint) equal to '1.'

For example, how can one define the following constraint in Mathcad?

x + y + z = 1

Below is simplified quadratic problem to be solved:

Minimize 3x^2 +2y^2 +z^2 + 2xy - xz - 0.8yz ...

subject to:

x + y + z = 1
x >= 0
y >= 0
z >= 0

Thanks for help.
 
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  • #2
In Mathcad, the constraint x + y + z = 1 can be written as: x + y + z - 1 = 0. Then, this constraint can be added to the list of constraints in the quadratic problem. The complete set of constraints should then look like this: x + y + z - 1 = 0x >= 0y >= 0z >= 0
 

1. What is the purpose of defining Mathcad variables to be equal to unity?

Defining Mathcad variables to be equal to unity is useful for simplifying equations and making them easier to solve. It also helps to avoid errors and confusion when working with complex equations.

2. How do I define a Mathcad variable to be equal to unity?

To define a Mathcad variable to be equal to unity, simply use the assignment operator := and set the variable equal to the numerical value 1. For example: x := 1.

3. Can I define multiple variables to be equal to unity at once?

Yes, you can define multiple variables to be equal to unity by separating them with commas within the assignment statement. For example: x, y, z := 1.

4. Is there a difference between using "=" and ":=" when defining Mathcad variables to be equal to unity?

Yes, there is a difference between the two operators. The "=" operator is used for equality testing, while ":=" is used for variable assignment. When defining variables to be equal to unity, it is important to use ":=" to assign the correct value.

5. Can I redefine a variable to be equal to unity after it has already been assigned a different value?

Yes, you can redefine a variable to be equal to unity even if it has already been assigned a different value. However, this may affect other equations or calculations that use the variable, so it is important to be cautious when redefining variables.

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