Matlab exercises -- program control process exercise

matlab Series articles ： Catalog

One 、 subject

• (1) Building functions , The input variables are sorted by month, year and day 8 An integer （ Such as 20220530）, The output variable is the ordinal number of the date in the year
• (2) It is known that 2022 year 1 month 1 Day is Saturday , Building functions , The input variables are sorted by month, year and day 8 An integer （ Such as 20220530), Output the day of the week
• (3) Definition 10 That's ok 8 Column Hilbert matrix （$a_{ij=\frac{1}{i+j-1}}$）
• (4) Generate 100000 The Fibonacci series within ,$a_1=1,a_2=2,a_n=a_{n-1}+a_{n-2},n=3,4,5,...$
• (5) To satisfy the condition $n!>10^{15}$ Minimum integer of
• (6) Output all five pointed star numbers （ for example 54748,$5^5+4^5+7^5+4^5+8^5=54748$）
• (7) Interactive input of three real numbers , If this three numbers as the side length can form a triangle , Find the area
• (8) Programming calculation of chicken and rabbit in the same cage （ Thirty five heads , Ninety four feet ）
• (9) Drawing piecewise functions $$f(x)=\{\begin{array}{rlr}& -x,& -5\text{<}x\text{<}0\\ & & \\ & \frac{x^2}{2},& 0\le x\le 2\\ & & \\ & 2sin(\frac{\pi }{x}),& 2\text{<}x\text{<}5\end{array}$$
• (10) Reading data sd.xlsx, Yes 1,2 Column calculates its sum for each row , And greater than 6 In the 3 Enter letters... In the corresponding row of the column A, Otherwise, enter the letters B, Yes 4,5 Column calculates the difference for each row , Difference greater than 2 In the 6 Enter letters... In the corresponding row of the column AB, Otherwise, enter the letters BA, And fill in the data after the operation sd.xlsx

Two 、 answer

Topic 1

① Building functions , The input variables are sorted by month, year and day 8 An integer （ Such as 20220530）, The output variable is the ordinal number of the date in the year

function out = getNum(date)

date_str = num2str(date);
 
d = [strcat(date_str(1:4),'-',date_str(5:6),'-',date_str(7:8))];

d_new = [strcat(date_str(1:4),'-01-01')];

out = daysact(d_new,d);

end

Topic two

① It is known that 2022 year 1 month 1 Day is Saturday , Building functions , The input variables are sorted by month, year and day 8 An integer （ Such as 20220530), Output the day of the week

function out = getNum(date)

date_str = num2str(date);

d = [strcat(date_str(1:4),'-',date_str(5:6),'-',date_str(7:8))];

out = weekday(d);

end

Question three

① Definition 10 That's ok 8 Column Hilbert matrix （$a_{ij=\frac{1}{i+j-1}}$）

function m = Hilber()
for i=1:10
    for j=1:8
        a(i,j) = 1/(i+j-1);
    end
end
m = a;
end

Question 4

① Generate 100000 The Fibonacci series within ,$a_1=1,a_2=2,a_n=a_{n-1}+a_{n-2},n=3,4,5,...$

function fib_arr = fib(k)
    num(1) = 1;
    num(2) = 1;
    for i=3:k
        num(i) = num(i-1) + num(i-2);
        if num(i) >= k
            break
        end
        fib_arr = num(1:end-1);
end

Question five

① To satisfy the condition $n!>10^{15}$ Minimum integer of

function out = getNum()
num(1) = 1;
for i = 1:1000000
    if(num(i) > 10^15)
        break
    end
    num(i+1) = num(i)*i
end

out = num(end-1);
    
end

Question six

① Output all five pointed star numbers （ for example 54748,$5^5+4^5+7^5+4^5+8^5=54748$）

function out = getNum()
count = 0;
for i=10000:99999
    a = fix(i/10000);
    b = fix(rem(i,10000)/1000);
    c = fix(rem(i,1000)/100);
    d = fix(rem(i,100)/10);
    e = fix(rem(i,10)/1);
    if(a^5+b^5+c^5+d^5+e^5==i)
        count = count + 1;
        num(count) = i;
    end
end
out = num;
end

Question seven

① Interactive input of three real numbers , If this three numbers as the side length can form a triangle , Find the area

function out = getNum(a,b,c)
if(a+b>c && a-b<c)
    p = (a+b+c)/2;
    s = (p*(p-a)*(p-b)*(p-c))^(1/2);
end

out = s;
end

Question eight

① Programming calculation of chicken and rabbit in the same cage （ Thirty five heads , Ninety four feet ）

function out = getNum()
syms x y;
enq1 = x + y == 35;
enq2 = 2*x + 4*y == 94;
A = solve(enq1,enq2,x,y);
out = A;
end

Question nine

① Drawing piecewise functions

x=-5:.1:5;
f=zeros(size(x));
for i=1:length(x)
    if (x(i)>-5) & (x(i)<0)
        f = -x
    end
    if (x(i)>=0) & (x(i)<=2)
        f = x.^2/2
    end
    if (x(i)>2) & (x(i)<5)
        f = 2*sin(pi./x)
    end
end
plot(f,x)

Question 10

① Reading data sd.xlsx, And fill in the data after the operation sd.xlsx

• Program 1

data1=xlsread('F:\sd.xlsx',1,'A1:B191')
for i = 1:length(data1)
if data1(i,1)+data1(i,2)>6
xlswrite('F:\sd.xlsx','A',1,strcat('C',num2str(i)))
else
xlswrite('F:\sd.xlsx','B',1,strcat('C',num2str(i)))
end
end

• Program two

data2=xlsread('F:\sd.xlsx',1,'D1:E191')
for i = 1:length(data2)
if abs(data2(i,1)-data2(i,2))>2
xlswrite('F:\sd.xlsx',{
    'AB'},1,strcat('F',num2str(i)))
else
xlswrite('F:\sd.xlsx',{
    'BA'},1,strcat('F',num2str(i)))
end
end