Suppose I have a textbox called inputfunction and a label called outputfunction. I press a button and this is the code

Dim variable as Object

variable = inputfunction.Text

outputfunction.Text = variable

Ok, If I type in the number 4 in the textbox, I get 4 in the label
What I want is to type in a mathematical expression as a string, and make my "variable" not a string but into a segment of code. Basically I want it so when I type in "2 + 2" it will give me 4 in the label. When I type in sqrt(4) I want it to give me 2 in the label instead of an error message. How do I convert the String into a mathematical expression that visualbasic.net can read as a code insertion?