# difference

12. ### Percent change vs percent difference

I'm having trouble wrapping my mind around this simple concept. I could really use an outside perspective. Here is the situation : Any dose given to a patient must be within 10% of the prescribed dose. If the prescribed dose is 2.14 mg and the dose given was 2.29 mg what formula should I be...
13. ### Having issues with expressing a trig problem as a sum or difference.

I recently came across this question: cosAcos4A I have never dealt with anything higher than cos2A, but I'm guessing you have to split the cos4A into cos(2A+2A), and solve that way. Is there a way to express this as a single cos value? It seems like this takes a million steps to simplify. So...
14. ### summation of difference

Can anyone explain why the formula of any term is f(r) -f(r-1) ???
15. ### Find the Difference between Positive and Negative Numbers.Result Needs to be Positive

I'm trying to find an equation to find the difference between two numbers, and have the result be positive regardless of whether the result is negative or positive. For example, if X = 600 and Y = 300 then the difference would be 300 using X - Y, however if X = -600 and Y = -300 then the...
16. ### The Difference between a Gradient and the good ol' derivatives?

What is the difference between a Gradient and the good ol' derivatives? and how does a gradient help us get the derivative in any direction? Edit: I did some reading here http://betterexplained.com/articles/vector-calculus-understanding-the-gradient/ and the author says: Why is that true...
17. ### Finite difference method nonlinear PDE Problem

i want to solve a nonlinear PDE with finite difference method , from my academic background , i know how to use finite difference method to solve linear PDE , what's the right way to use FDM to solve nonlinear PDE or could someone provide me with book's titles or articles that can help me...
18. ### Difference equation gone wrong

The picture says it all, sorry for the scribbles
19. ### Difference of proportion hypothesis test

If I am given two samples of the rate of production of 2 factory conveyor belts, and I am asked to perform a hypothesis test on whether one produces more per hour by 5%. How do I calculate the percentage difference. Is it as simple as setting the null and alternative hypothesis to be equal to...
20. ### Logistic Difference Equation

The logistic difference equation can be made dimensionless and rewritten in the simpler form: Xn+1 = f (Xn) (1) if we introduce (a) Find the function f ; (Hint: you can denote ) (b) Consider the logistic map given by the equation (1) for all real X and for any a>1. i. Show that if Xn > 1 for...