Numerical Methods Fourier Transform Pair Part: Frequency and Time Domain http://numericalmethods.eng.usf.edu

# Numerical Methods Fourier Transform Pair Part: Frequency and Time Domain http://numericalmethods.eng.usf.edu

## Numerical Methods Fourier Transform Pair Part: Frequency and Time Domain http://numericalmethods.eng.usf.edu

- - - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - - -
##### Presentation Transcript

1. Numerical MethodsFourier Transform PairPart: Frequency and Time Domainhttp://numericalmethods.eng.usf.edu

2. For more details on this topic • Go to http://numericalmethods.eng.usf.edu • Click on keyword • Click on Fourier Transform Pair

3. You are free • to Share – to copy, distribute, display and perform the work • to Remix – to make derivative works

4. Under the following conditions • Attribution — You must attribute the work in the manner specified by the author or licensor (but not in any way that suggests that they endorse you or your use of the work). • Noncommercial — You may not use this work for commercial purposes. • Share Alike — If you alter, transform, or build upon this work, you may distribute the resulting work only under the same or similar license to this one.

5. Chapter 11.03: Fourier Transform Pair: Frequency and Time Domain Lecture # 5 Major: All Engineering Majors Authors: Duc Nguyen http://numericalmethods.eng.usf.edu Numerical Methods for STEM undergraduates 6/2/2014 http://numericalmethods.eng.usf.edu 5

6. Example 1 6 http://numericalmethods.eng.usf.edu

7. Frequency and Time Domain The amplitude (vertical axis) of a given periodic function can be plotted versus time (horizontal axis), but it can also be plotted in the frequency domain as shown in Figure 2. Figure 2 Periodic function (see Example 1 in Chapter 11.02 Continuous Fourier Series) in frequency domain. http://numericalmethods.eng.usf.edu

8. Frequency and Time Domain cont. Figures 2(a) and 2(b) can be described with the following equations from chapter 11.02, (39, repeated) where (41, repeated) 8 http://numericalmethods.eng.usf.edu

9. Frequency and Time Domain cont. For the periodic function shown in Example 1 of Chapter 11.02 (Figure 1), one has: http://numericalmethods.eng.usf.edu

10. Frequency and Time Domain cont. Define: or 10 http://numericalmethods.eng.usf.edu

11. Frequency and Time Domain cont. Also, http://numericalmethods.eng.usf.edu

12. Frequency and Time Domain cont. Thus: Using the following Euler identities 12 http://numericalmethods.eng.usf.edu

13. 1 Noting that for any integer Frequency and Time Domain cont. http://numericalmethods.eng.usf.edu

14. Frequency and Time Domain cont. Also, Thus, 14 http://numericalmethods.eng.usf.edu

15. Frequency and Time Domain cont. From Equation (36, Ch. 11.02), one has (36, repeated) Hence; upon comparing the previous 2 equations, one concludes: http://numericalmethods.eng.usf.edu

16. Frequency and Time Domain cont. For the values for and (based on the previous 2 formulas) are exactly identical as the ones presented earlier in Example 1 ofChapter 11.02. 16 http://numericalmethods.eng.usf.edu

17. Frequency and Time Domain cont. Thus: 17 http://numericalmethods.eng.usf.edu

18. Frequency and Time Domain cont. http://numericalmethods.eng.usf.edu

19. Frequency and Time Domain cont. 19 http://numericalmethods.eng.usf.edu

20. Frequency and Time Domain cont. In general, one has http://numericalmethods.eng.usf.edu

21. The End http://numericalmethods.eng.usf.edu

22. Acknowledgement This instructional power point brought to you by Numerical Methods for STEM undergraduate http://numericalmethods.eng.usf.edu Committed to bringing numerical methods to the undergraduate

23. For instructional videos on other topics, go to http://numericalmethods.eng.usf.edu/videos/ This material is based upon work supported by the National Science Foundation under Grant # 0717624. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.

24. The End - Really

25. Numerical MethodsFourier Transform Pair Part: Complex Number in Polar Coordinateshttp://numericalmethods.eng.usf.edu

26. For more details on this topic • Go to http://numericalmethods.eng.usf.edu • Click on keyword • Click on Fourier Transform Pair

27. You are free • to Share – to copy, distribute, display and perform the work • to Remix – to make derivative works

28. Under the following conditions • Attribution — You must attribute the work in the manner specified by the author or licensor (but not in any way that suggests that they endorse you or your use of the work). • Noncommercial — You may not use this work for commercial purposes. • Share Alike — If you alter, transform, or build upon this work, you may distribute the resulting work only under the same or similar license to this one.

29. In Cartesian (Rectangular) Coordinates, a complex number can be expressed as: In Polar Coordinates, a complex number can be expressed as: Lecture # 6 Chapter 11.03: Complex number in polar coordinates (Contd.) 29 http://numericalmethods.eng.usf.edu

30. Complex number in polar coordinates cont. Thus, one obtains the following relations between the Cartesian and polar coordinate systems: This is represented graphically in Figure 3. Figure 3. Graphical representation of the complex number system in polar coordinates. 30 http://numericalmethods.eng.usf.edu

31. Complex number in polar coordinates cont. Hence and 31 http://numericalmethods.eng.usf.edu

32. Complex number in polar coordinates cont. Based on the above 3 formulas, the complex numbers can be expressed as: http://numericalmethods.eng.usf.edu

33. Complex number in polar coordinates cont. Notes: • The amplitude and angle are 0.59 and • 2.14 respectively (also see Figures 2a, and • 2b in chapter 11.03). (b) The angle (in radian) obtained from will be 2.138 radians (=122.48o). However based on Then = 1.004 radians (=57.52o). http://numericalmethods.eng.usf.edu

34. Complex number in polar coordinates cont. Since the Real and Imaginary components of are negative and positive, respectively, the proper selection for should be 2.1377 radians. http://numericalmethods.eng.usf.edu

35. Complex number in polar coordinates cont. 35 http://numericalmethods.eng.usf.edu

36. Complex number in polar coordinates cont. http://numericalmethods.eng.usf.edu

37. The End http://numericalmethods.eng.usf.edu

38. Acknowledgement This instructional power point brought to you by Numerical Methods for STEM undergraduate http://numericalmethods.eng.usf.edu Committed to bringing numerical methods to the undergraduate

39. For instructional videos on other topics, go to http://numericalmethods.eng.usf.edu/videos/ This material is based upon work supported by the National Science Foundation under Grant # 0717624. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.

40. The End - Really

41. Numerical MethodsFourier Transform Pair Part: Non-Periodic Functionshttp://numericalmethods.eng.usf.edu

42. For more details on this topic • Go to http://numericalmethods.eng.usf.edu • Click on keyword • Click on Fourier Transform Pair

43. You are free • to Share – to copy, distribute, display and perform the work • to Remix – to make derivative works

44. Under the following conditions • Attribution — You must attribute the work in the manner specified by the author or licensor (but not in any way that suggests that they endorse you or your use of the work). • Noncommercial — You may not use this work for commercial purposes. • Share Alike — If you alter, transform, or build upon this work, you may distribute the resulting work only under the same or similar license to this one.

45. Lecture # 7 Chapter 11. 03: Non-Periodic Functions (Contd.) Recall (39, repeated) (41, repeated) Define (1) 45 http://numericalmethods.eng.usf.edu

46. Non-Periodic Functions Then, Equation (41) can be written as And Equation (39) becomes From above equation or http://numericalmethods.eng.usf.edu

47. Non-Periodic Functions cont. From Figure 4, Figure 4. Frequency are discretized. 47 http://numericalmethods.eng.usf.edu

48. Non-Periodic Functions cont. Multiplying and dividing the right-hand-side of the equation by , one obtains ; inverse Fourier transform Also, using the definition stated in Equation (1), one gets ; Fourier transform 48 http://numericalmethods.eng.usf.edu

49. The End http://numericalmethods.eng.usf.edu

50. Acknowledgement This instructional power point brought to you by Numerical Methods for STEM undergraduate http://numericalmethods.eng.usf.edu Committed to bringing numerical methods to the undergraduate