Question :
a : Write Matlab code in the M-file (q2.m) that will read data from ‘LightTransmit.txt' (skip the text lines). Unfortunately, there is ‘noise' in the dataset (those data with It value higher than 10) and your Matlab program should skip those data as well and store the rest of the data in a matrix called ‘transmission_data'. You should not use import wizard to load the data from the text file.
Then, use the scatter command to create a scatterplot of data with intensity of light transmission, It, versus thickness (in metres) of the transparent solid, L. You need to include appropriate title, legend and label of x-axis and y-axis in your plot which should be the top left subplot in the figure you create.
b : Based on the data distribution pattern observed in your scatter plot from Q2a, you predict the relationship between the intensity of light transmission and the transparent solid length could possibly be related by a polynomial equation.
Perform a polynomial fit with a third order polynomial and make a plot for the polynomial equation over the range of the data which is overlaid with the scatter plot from (i.e., this should be plotted in the top left subplot also). You should also create 50 interpolated data points onto your sub plot which are shown as red dots.
Hint: You can use the Matlab built-in functions polyfit and polyval for this task.
By observing the plot you made for the task above, your polynomial model seemingly fit the existing data points well. Try to create an extrapolated plot by extending the L upper limit to 0.16 m. Place your extrapolated plot in the top right subplot in the figure.
What do you observe and conclude from your extrapolated plot? Use fprintf to write brief description of the problem you see in the curve fit.
data in LightTransmit.txt is like:
L(cm) IT (watts/m2)
0.5 4.2 0.7 12 1.2 4.0 1.7 3.8 2.0 15 2.2 3.6 3.5 3.2 4.2 3.0 4.5 2.9 5.0 10.8 6.0 2.5