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Advanced Plotting 2(Example from Aj.Jim)

ผศ.ดร.อนั�นัต์ ผลเพิ่��มAnan Phonphoem

http://www.cpe.ku.ac.th/~anananan@cpe.ku.ac.th

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Inventory Problem

Here are projected sales for 10 weeks:Week: 1 2 3 4 5 6 7 8 9 10 Sales: 700 1100 800 800 1000 2200 1100 900 1000 1100 Each week the company can manufacture 1,000 units, and

only sells units that are finished and "in stock".So the sales & inventory balance for week k is:

Production = 1000

Sales(k) = minimum( ProjectedSales(k), Inventory(k) )

Inventory(k+1) = Inventory(k) + Production - Sales(k) Starting inventory at week 1 is 200. Compute the actual

sales.

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Inventory Problem Formulation

1. Formulate your solution method on paper.

2. Write a flow chart for your solution on paper.

3. Create an m-File to implement the flow chart.

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Inventory Problem Solution (1)

3. Create an m-File to implement the flow chart.% Projected sales for each weekpsales = [ 700 1100 800 800 1000 2200 1100 900 1000 1100 ];% Production each weekproduction = 1000;% Initial inventory:inventory(1) = 200;% Inventory - sales - production balance for week ksales(k) = min( psales(k), inventory(k) );inventory(k + 1) = inventory(k) + production - sales(k);

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Inventory Problem Solution (2)

3b. Add a "for" loop for each week...% SalesForecast.m% Projected sales for each weekpsales = [700 1100 800 800 1000 2200 1100 900 1000 1100 ];% Production each weekproduction = 1000;% Initial inventory:inventory(1) = 200;% Inventory - sales balance for week kfor k=1:10 sales(k) = min( psales(k), inventory(k) ); inventory(k + 1) = inventory(k) + production - sales(k);end

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Inventory Problem Solution (3)

Run the m-file and view the actual sales:>> SalesForecast>> salessales = 200 1000 800 800 1000 1400 900 900 1000 1100

>> sum( sales )ans = 9200

Too many numbers to interpret. What were the total sales?

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Inventory Problem Solution (4)

>> psales - salesans = 500 100 0 0 0 800 100 0 0 0

How many sales were "lost" due to insufficient "stock"?

Maybe we should hire some O.T. during week 1, 5, and 6 to increase production during those weeks?

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Inventory Problem Solution (5)

Plot proj. sales, actual sales, and inventory on one plot:

>> week = 1:10>> plot( week, psales, 'bo:', week, sales, 'gp--',

week, inventory(1:10), 'rx' )>> legend( 'projected sales', 'sales', 'inventory' )

0 2 4 6 8 10200

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2200

projjected salessalesinventory

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Inventory Problem Solution (6)

Plot projected sales, sales, and excess inventory.

>> week = 1:10>> plot( week, psales, 'bo:', week, sales, 'gp--',

week, inventory(1:10)-sales, 'r^' )>> legend( 'projected sales', 'sales', 'excess inventory' )

0 2 4 6 8 100

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projjected salessalesexcess inventory

Hmmm... not much surplus inventory in weeks 6-10. If sales are high, we're in bad shape.