The problems below are designed to introduce work with MATLAB and to do some basic data manipulation and simple programming. The data in the file ppt.dat are precipitation in mm for the Southern Piedmont of the U.S. (Karl et al. 1994). The rows represent years from 1960 through 1989, and the columns represent months from January to December.

JAN	FEB	MAR	APR	MAY	JUN	JUL	AUG	SEP	OCT	NOV	DEC
133.8	157.6	120.9	84.5	87.5	71.3	130.0	112.7	100.1	55.2	28.0	48.1
70.4	153.6	115.7	136.7	91.7	143.1	96.4	159.4	35.6	44.8	54.2	127.1
139.2	100.0	124.7	94.4	63.3	136.0	96.4	77.0	121.5	35.6	130.1	73.1
92.0	78.5	127.1	69.3	80.2	106.5	87.5	53.9	114.0	4.7	135.7	70.3
142.7	125.5	129.5	118.6	51.9	90.1	170.1	166.0	84.4	178.4	49.6	111.8
48.9	104.7	159.1	81.7	46.6	157.4	151.6	89.5	68.2	64.3	44.1	15.8
130.5	109.0	69.8	67.7	116.2	75.6	77.5	94.7	130.9	74.9	40.1	78.5
62.5	86.9	67.3	55.3	127.3	73.8	115.7	176.8	64.2	40.4	68.0	123.0
111.9	19.4	79.4	68.4	107.9	125.4	138.9	69.0	34.3	92.6	107.1	69.3
64.8	84.8	103.6	112.5	84.8	107.2	120.5	123.6	105.2	37.6	37.1	114.4
58.5	79.4	121.5	66.6	75.9	67.9	136.5	140.7	50.1	125.8	63.6	75.3
100.1	116.5	133.8	73.8	153.0	87.5	147.7	137.7	108.9	171.9	69.5	43.7
107.8	108.1	75.3	58.0	145.9	181.2	117.4	86.1	84.0	89.2	125.7	140.2
97.9	114.1	144.2	126.6	109.0	172.1	85.7	101.5	72.9	60.5	27.9	146.6
122.4	90.2	78.6	66.4	126.9	91.1	91.4	139.6	121.0	14.4	61.5	132.5
137.9	108.9	185.7	66.0	141.0	90.3	213.7	71.7	182.5	58.7	71.6	94.5
84.0	36.5	98.0	24.2	146.3	144.2	85.4	66.2	116.3	184.6	77.2	107.6
68.3	31.9	145.1	52.5	60.7	84.0	54.8	114.9	111.8	134.6	103.4	89.7
199.0	22.2	111.0	101.5	116.5	95.6	140.7	116.0	54.9	28.9	75.8	76.3
148.8	157.4	84.4	134.4	116.3	131.2	95.9	93.8	208.8	77.9	109.4	35.6
120.7	42.6	211.3	68.3	86.3	80.3	82.5	53.5	128.2	88.4	72.6	29.9
17.1	98.0	58.5	45.2	75.9	102.4	146.0	123.2	72.5	82.8	24.0	139.6
120.3	131.1	57.3	114.4	93.7	170.0	118.4	93.9	67.0	88.2	74.0	106.4
68.4	126.5	176.7	147.2	81.6	79.2	51.5	79.7	77.2	98.0	119.4	172.8
95.1	137.5	148.7	119.5	142.1	62.9	207.8	113.0	19.7	57.0	52.4	49.2
92.4	124.4	26.5	28.9	104.3	85.5	158.1	166.1	17.3	115.3	213.2	31.9
33.8	50.3	67.4	28.7	67.8	36.4	83.5	192.1	35.7	85.7	118.2	101.6
153.5	98.3	117.9	107.2	56.3	116.3	73.7	75.8	193.0	32.1	98.2	70.5
85.7	44.5	60.7	71.7	86.7	73.2	102.7	109.1	109.3	74.1	96.7	22.2
53.6	112.3	131.4	102.9	135.7	172.8	178.8	99.6	131.1	121.9	71.1	80.3

Solve the following five problems and turn in all MATLAB files and needed figures.

Additional requirement:

(1) Plot the results of Problems 2 3 in another figure. (tip: use figure to open new figure window)

(2) Comment on each line of the M-file of problem 3

1. Read the data into MATLAB.

2. Write an m-file program to: (a) query for a year (see the input command); (b) for the selected year, calculate and display the minimum, maximum, and mean monthy precipitation (see the min and max commands); (c) make a stem plot of the data (see the stem command), labelling the axes and placing an appropriate title (see the xlabel, ylabel and title commands).

3. Write a function file that accepts an N M matrix (such as the precipitation file) as an argument, finds the maximum correlation coefficient (absolute value) between any two columns of the data, reports that value as output, and presents a scatter plot of the two columns of data with maximal correlation. Apply the code to the precipitation file and briefly comment on any interpretation of the result. (You may want to use corrcoef and eye.)