How to simulate the number of ice-creams sold per hour ?

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Jabir Al Fatah 2014-6-2

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https://ww2.mathworks.cn/matlabcentral/answers/132148-how-to-simulate-the-number-of-ice-creams-sold-per-hour

评论： Jabir Al Fatah 2014-6-3

I have the following code and I need to adjust the value of Am, B and D so that the cosine function shows the 1st and 24th rows are roughly equal to 50 and 12th row is roughly equal to 5. Now I have played with the values more than 100 times but none of them meets the condition.

    Am=20;%Amplitude, play with the value 
B=6;%Frequency,play with the value 
C=0;%Phase, the phase's value is constant, it won't be changed 
D=14;%Offset, play with the value 
for j=1:7;%makes 7 columns 
for i=1:24;%makes 24 rows 
A(i,j)=Am*cos(B*i+C)+D 
end 
end 
surf(A)%plots a cosine curve

[NOTE: The 24 rows represents the 24 hours (first row is 12 o'clock at noon) and 7 columns represents the 7 days in a week. The requirement is : Simulate the number of icecreams sold per hour during one week in a particular store in a warm summer week. We accept fractional number of icecreams ! Suppose that a icecream store sells about 50 icecreams per hour at noon, and about 5 icecreams per hour at midnight. Lets have a random fluctuation of about +/- 2 icecreams per hour. Lets start by assuming that every weekday has the same icecream sales.]

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Answer 1

Image Analyst 2014-6-2

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https://ww2.mathworks.cn/matlabcentral/answers/132148-how-to-simulate-the-number-of-ice-creams-sold-per-hour#answer_139225

在 MATLAB Online 中打开

Hint: Try this:

clc
Am = 45/2;%Amplitude, play with the value
period = 24;%Frequency,play with the value
phase = 12;%Phase, the phase's value is constant, it won't be changed
offset = 5;%Offset, play with the value
theHour = 1:24; %makes 24 rows
A = Am * (1 + cos(2*pi*(theHour+phase)/period)) + offset
plot(A, 'bs-', 'LineWidth', 3)%plots a cosine curve
grid on;
xlim([1, 24]);
ylim([0, 55]);

Try adding noise (variation in # sales) with the rand() function.

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Jabir Al Fatah 2014-6-3

在 MATLAB Online 中打开

Your answer showed me the right way. I just modified it so that it meets my exact expectation:

    Am = 45/2;%Amplitude, play with the value
B = 24;%Frequency,play with the value
C = 0;%Phase, it's initially set as zero
D = 5;%Offset, play with the value
for j = 1:7
for i= 1:24
A(i,j) = Am *(1+cos(2*pi*(i+C)/B))+D
end
end
surf(A)