Arrays Numerical Data Files

1. ArraysNumerical Data Files dlmread()

2. Decide which function to use?

3. “Unique Delimiter” • “Neatly Organized” • Rows and Columns are “identifiable” • No “holes” anywhere • Always the same patterns per line • There is no mixes of delimiters (commas, spaces, tabs, dash.. )

4. dlmread() ok?

5. Documentation of dlmread() dlmread Read ASCII-delimited file of numeric data into matrix. Syntax M = dlmread(filename) M = dlmread(filename, delimiter) M = dlmread(filename, delimiter, R, C) M = dlmread(filename, delimiter, range) Description M = dlmread(filename) reads the ASCII-delimited numeric data file filename, and returns the data in output matrix M. The filename input is a string enclosed in single quotes. dlmread infers the delimiter from the formatting of the file.

6. Example 1 Airfoils & Plotting

7. Example Aerospace NACA Airfoils The NACA airfoils are airfoils shapes for aircraft wings developed by the National Advisory Committee for Aeronautics (NACA). (Wikipedia) http://en.wikipedia.org/wiki/NACA_airfoil http://www.ae.illinois.edu/m-selig/ads/coord_database.html#N

8. Current Project from Tutor Michael Gondek

9. Example Aerospace NACA Airfoils Once uploaded into arrays, and using slicing to extract the x and y coordinates, it is easy to plot the airfoil in MATLAB.

10. Example 2 Analyzing Sales

11. Example Analyzing sales Email from the client: “Please find attached the file. Sum up the last column for each month. Months are in column 2, and will be in the right order. This is a small test file, we’ll email you the big one when we have it. Email us the results. Thanks.”

12. Example Analyzing sales Sovle by hand: For September: (easy..) $153,440 For October: 135,500 + 147,000 -> $282,500 For December: 154,000+168,000 -> $322,000

13. Key Points • Vocabulary: delimiters • Recognizing if dlmread() will work with the specific input file. • Using dlmread() with the whitespace delimiter (airfoils) • Using dlmread() with the dash delimiter (sales)