# Help ly needed in Mathematica Simplify

• Mathematica
• Neitrino
In summary, the person is seeking urgent help with simplifying a long expression involving variables x, a, and Lambda. They were able to simplify it to only involve Lambda, but when they set a = 1 and attempted to simplify again, it gave them zero. They are wondering why this happens and asking for assistance. Another person suggests that there may be some divide by zero errors causing the issue.
Neitrino
Help urgently needed in Mathematica Simplify

Dear All,

I have a very longe expression (see file attached ) of variables x, a, Lambda... etc,
when I apply "Simplify" I am left only with very short expression
ONLY with variable Lambda.

But if in the initial expression I declare "a" variable as equal to one (a = 1) and afterwrds try to do simplification it gives me ZERO!.

So why this happen .. If the first "Simplify" tells me that the expression is dependent only on Lambda why "a" variable affects the result ...?

Pls heelp... what I do wrong...
George

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I assume there's some zeroes. The first answer is correct, as you can see if you do :
Limit[fx[a],a->1]
its the a independent solution. The second part (where it is 0) is most likely due to these divide by zeroes, where mathematica cannot correctly simplify it.

Dear George,

Thank you for reaching out for help with Mathematica Simplify. It is possible that the initial expression you are working with is too complex for Simplify to handle efficiently. In such cases, it might be helpful to try using other functions such as FullSimplify or Expand to see if they can simplify the expression further.

Alternatively, you can try using assumptions in Simplify to specify certain variables or parameters as constants. For example, you can try using the assumption "a \[Element] Reals" to treat a as a real number and see if that helps with the simplification.

If you are still having trouble, it would be helpful if you could provide a sample of your initial expression and the specific steps you are taking to simplify it, so that we can better understand the issue and provide targeted advice.

I hope this helps and please let me know if you have any further questions or concerns.

Best,

## 1. How can I simplify an expression in Mathematica?

To simplify an expression in Mathematica, you can use the Simplify function. This function takes in the expression as its argument and returns the simplified version. You can also specify additional assumptions or options to further simplify the expression.

## 2. What is the difference between Simplify and FullSimplify in Mathematica?

Simplify and FullSimplify are similar functions in Mathematica, but FullSimplify takes longer to run and can give more simplified results. FullSimplify uses more advanced algorithms and methods to simplify expressions, while Simplify uses simpler techniques. In most cases, Simplify should suffice, but if you want a more thorough simplification, you can use FullSimplify.

## 3. How do I simplify a specific part of an expression in Mathematica?

You can simplify a specific part of an expression in Mathematica by using the function SimplifyPart. This function takes in the expression and the specific part you want to simplify as its arguments. It then simplifies only that part and returns the simplified expression with the rest of the expression unchanged.

## 4. Can I simplify an expression with variables in Mathematica?

Yes, you can simplify expressions with variables in Mathematica. You can use the Simplify function and specify the assumptions about the variables using the Assumptions option. This will simplify the expression based on those assumptions. You can also use the function SimplifyVariables to simplify an expression by replacing variables with simpler expressions.

## 5. Is there a way to control the level of simplification in Mathematica?

Yes, you can control the level of simplification in Mathematica by using the TimeConstraint and ComplexityFunction options in the Simplify function. The TimeConstraint option specifies the maximum amount of time that Simplify will spend simplifying the expression, while the ComplexityFunction option allows you to specify a function that determines the complexity of an expression and can be used to guide the simplification process.

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