Re: Differentiation question...

On Oct 21, 8:27 pm, luca.pampar...@xxxxxxxxx wrote:
Hello all,

Been trying to figure some equations out... actually owe a lot to this
group for all the help people have given me. So, thanks!

I have a rectangular function with the jump function at + 1/2 and -1/2
and as someone pointed out the differentiation of this would have a
delta function at the same points. So, the books right the
differentiation as follows:

d/dx (rect(x)) = delta(x+ 1/2) - delta(x -1/2).

My question is when you do the differentiation, why do you have the
minus sign between the two terms....

A few different ways to look at this.

1. Imagine a function which had a finite slope
instead of the jump. The slope is positive at
x = -1/2 and negative at x = +1/2.

2. Call your function R(x). Consider the step
function
phi(x) = {0, x<0
{1, x>=0

Then R(x) = phi(x+1/2) - phi(x-1/2)

- Randy

.

Relevant Pages

  • Re: Differentiation question...
    ... actually owe a lot to this ... differentiation as follows: ... Simplest, I think, is to consider rectto be the sum of two ... shifted unit step functions. ...
    (sci.math)
  • Differentiation question...
    ... actually owe a lot to this ... So, the books right the ... differentiation as follows: ... minus sign between the two terms.... ...
    (sci.math)
Quantcast