- #1

- 194

- 0

For the last waveform in the picture above. How would i go about writing an equation for f(t)?

Thanks in advance

You are using an out of date browser. It may not display this or other websites correctly.

You should upgrade or use an alternative browser.

You should upgrade or use an alternative browser.

- Thread starter ACLerok
- Start date

- #1

- 194

- 0

For the last waveform in the picture above. How would i go about writing an equation for f(t)?

Thanks in advance

- #2

OlderDan

Science Advisor

Homework Helper

- 3,021

- 2

ACLerok said:

For the last waveform in the picture above. How would i go about writing an equation for f(t)?

Thanks in advance

As an absolute value of something, or as a piecewise definition for each of the intervals that has a continuous derivative.

- #3

- 194

- 0

- #4

OlderDan

Science Advisor

Homework Helper

- 3,021

- 2

ACLerok said:

The last waveform is called a Full-wave rectified sine. It is a sine function with all the negative regions flipped to positive. It is the absolute value of the sine function

[tex] f(x) = \left| {A\sin 2\pi \frac{t}{T}} \right| = A\left| {\sin 2\pi \frac{t}{T}} \right| [/tex]

or you could write separate functions for the separate intervals with alternating plus and minus signs in front of the sine function.

- #5

- 194

- 0

- #6

OlderDan

Science Advisor

Homework Helper

- 3,021

- 2

ACLerok said:

No. For one thing you need a variable, t, in the argument of the sine function (T is a constant) and you need to define the function to be zero in the intervals where the waveform is zero. One way to do that would be to take 1/2 times your second waveform and add A/2 so that the square wave is between 0 and A; then use that in place of the A in the sine function you have.

- #7

- 194

- 0

- #8

- 194

- 0

anyone? :(

- #9

OlderDan

Science Advisor

Homework Helper

- 3,021

- 2

ACLerok said:

I'm not sure what you are asking. For the full-wave rectified sine the function is a sine function from 0 to T

[tex] f(x) = A\sin \pi \frac{t}{T}} [/tex]

Between T and 2T it is

[tex] f(x) = -A\sin \pi \frac{t}{T}} [/tex]

There is no 1-t^2 involved

- #10

OlderDan

Science Advisor

Homework Helper

- 3,021

- 2

OlderDan said:The last waveform is called a Full-wave rectified sine. It is a sine function with all the negative regions flipped to positive. It is the absolute value of the sine function

[tex] f(x) = \left| {A\sin 2\pi \frac{t}{T}} \right| = A\left| {\sin 2\pi \frac{t}{T}} \right| [/tex]

or you could write separate functions for the separate intervals with alternating plus and minus signs in front of the sine function.

CORRECTION!

Sorry, I misinterpreted the T as being the period of the sine function. In fact 2T is the period in the figure. This should have been

[tex] f(x) = \left| {A\sin \pi \frac{t}{T}} \right| = A\left| {\sin \pi \frac{t}{T}} \right| [/tex]

- #11

OlderDan

Science Advisor

Homework Helper

- 3,021

- 2

ACLerok said:

From 0 to T/2 or from nT to (n+1/2)T this should be

[tex] f(x) = {A\sin 2\pi \frac{t}{T}} [/tex]

From T/2 to T or from (n+1/2)T to (n+1)T f(x) is zero.

Share: