How to define local variables and constants in mathematica

[yashar]

hi
suppose i run Two notebook and in each of them i have matrix A and Constant B and a function C
in each notebook these things have the same name.
if in notebook 1 i assign B=10 then in notebook 2 B is 10 too , which is not my desire.
how can i define these constants and matrices and functions so that they are not affect each other in each notebook.
i do not want to rename one of these entities.

thanks

 

[a-tom-ic]

You might want to clear the globals at the beginning of your notebook (only works if you process the notebook as a whole):
http://reference.wolfram.com/mathematica/howto/ClearMyDefinitions.html
Another option could be to use local variables:
http://reference.wolfram.com/mathematica/tutorial/ModulesAndLocalVariables.html

 

[Simon_Tyler]

You can handle this behaviour using Contexts. Under the Evaluation menu, choose "Notebook's Default Context" > "Unique to This Notebook".

Now each notebook will be using different name spaces, and the variables won't clash.

 

[yashar]

thanks

 

[alphy]

In Mathematica, local variables and constants can be defined using the "Module" function. This function creates a local environment in which variables and constants can be defined without affecting the global environment. To define a local variable, use the syntax "Module[{var1, var2, ...}, expression]". This will create a local environment where the variables var1, var2, etc. can be defined and used within the expression. Similarly, to define a local constant, use the syntax "Module[{const1 = value1, const2 = value2, ...}, expression]". This will create a local environment where the constants const1, const2, etc. can be defined and used within the expression.

In your case, you can create separate modules in each notebook to define the variables and constants with the same names without affecting each other. For example, in notebook 1, you can use the syntax "Module[{B = 10}, expression]" to define a local constant B with the value of 10. Similarly, in notebook 2, you can use the same syntax to define a local constant B with a different value without affecting the constant in notebook 1.

Additionally, you can also use the "Block" function to create a local environment for variables and constants. The syntax is similar to the "Module" function, but the variables and constants defined in the "Block" function will be temporary and will not affect the global environment.

In conclusion, to avoid conflicts between variables and constants with the same name in different notebooks, it is recommended to use the "Module" or "Block" function to create local environments for them. This will ensure that each notebook has its own set of variables and constants without affecting the others.