Interpolation From A Table

Here are the code. But the value after i input the data to use the interpolation the value is wrong. Could anyone help me figure this out ?

clear
clc

Table = [0.04 28.96 1.0040 34.800 121.45 2415.2 121.46 2432.9 2554.4 0.4226 8.4746 0.04;
0.06 36.16 1.0064 23.739 151.53 2425.0 151.53 2415.9 2567.4 0.5210 8.3304 0.06;
0.08 41.51 1.0084 18.103 173.87 2432.2 173.88 2403.1 2577.0 0.5926 8.2287 0.08;
0.10 45.81 1.0102 14.674 191.82 2437.9 191.83 2392.8 2584.7 0.6493 8.1502 0.10;
0.20 60.06 1.0172 7.649 251.38 2456.7 251.40 2358.3 2609.7 0.8320 7.9085 0.20;
0.30 69.10 1.0223 5.229 289.20 2468.4 289.23 2336.1 2625.3 0.9439 7.7686 0.30;
0.40 75.87 1.0265 3.993 317.53 2477.0 317.58 2319.2 2636.8 1.0259 7.6700 0.40;
0.50 81.33 1.0300 3.240 340.44 2483.9 340.49 2305.4 2645.9 1.0910 7.5939 0.50;
0.60 85.94 1.0331 2.732 359.79 2489.6 359.86 2293.6 2653.5 1.1453 7.5320 0.60;
0.70 89.95 1.0360 2.365 376.63 2494.5 376.70 2283.3 2660.0 1.1919 7.4797 0.70;
0.80 93.50 1.0380 2.087 391.58 2498.8 391.66 2274.1 2665.8 1.2329 7.4346 0.80;
0.90 96.71 1.0410 1.869 405.06 2502.6 405.15 2265.7 2670.9 1.2695 7.3949 0.90;
1.00 99.63 1.0432 1.694 417.36 2506.1 417.46 2258.0 2675.5 1.3026 7.3594 1.00;
1.50 111.4 1.0528 1.159 466.94 2519.7 467.11 2226.5 2693.6 1.4336 7.2233 1.50;
2.00 120.2 1.0605 0.8857 504.49 2529.5 504.70 2201.9 2706.7 1.5301 7.1271 2.00;
2.50 127.4 1.0672 0.7187 535.10 2537.2 535.37 2181.5 2716.9 1.6072 7.0527 2.50;
3.00 133.6 1.0732 0.6058 561.15 2543.6 561.47 2163.8 2725.3 1.6718 6.9919 3.00;
3.50 138.9 1.0786 0.5243 583.95 2546.9 584.33 2148.1 2732.4 1.7275 6.9405 3.50;
4.00 143.6 1.0836 0.4625 604.31 2553.6 604.74 2133.8 2738.6 1.7766 6.8959 4.00;
4.50 147.9 1.0882 0.4140 622.25 2557.6 623.25 2120.7 2743.9 1.8207 6.8565 4.50;
5.00 151.9 1.0926 0.3749 639.68 2561.2 640.23 2108.5 2748.7 1.8607 6.8212 5.00;
6.00 158.9 1.1006 0.3157 669.90 2567.4 670.56 2086.3 2756.8 1.9312 6.7600 6.00;
7.00 165.0 1.1080 0.2729 696.44 2572.5 697.22 2066.3 2763.5 1.9922 6.7080 7.00;
8.00 170.4 1.1148 0.2404 720.22 2576.8 721.11 2048.0 2769.1 2.0462 6.6628 8.00;
9.00 175.4 1.1212 0.2150 741.83 2580.5 742.83 2031.1 2773.9 2.0946 6.6226 9.00;
10.0 179.9 1.1273 0.1944 761.68 2583.6 762.81 2015.3 2778.1 2.1387 6.5863 10.0;
15.0 198.3 1.1539 0.1318 843.16 2594.5 844.84 1947.3 2792.2 2.3150 6.4448 15.0;
20.0 212.4 1.1767 0.09963 906.44 2600.3 908.79 1890.7 2799.5 2.4474 6.3409 20.0;
25.0 224.0 1.1973 0.07998 959.11 2603.1 962.11 1841.0 2803.1 2.5547 6.2575 25.0;
30.0 233.9 1.2165 0.06668 1004.8 2604.1 1008.4 1795.7 2804.2 2.6457 6.1869 30.0;
35.0 242.6 1.2347 0.05707 1045.4 2603.7 1049.8 1753.7 2803.4 2.7253 6.1253 35.0;
40.0 250.4 1.2522 0.04978 1082.3 2602.3 1087.3 1714.1 2801.4 2.7964 6.0701 40.0;
45.0 257.5 1.2692 0.04406 1116.2 2600.1 1121.9 1676.4 2798.3 2.8610 6.0199 45.0;
50.0 264.0 1.2859 0.03944 1147.8 2597.1 1154.2 1640.1 2794.3 2.9202 5.9734 50.0;
60.0 275.6 1.3187 0.03244 1205.4 2589.7 1213.4 1571.0 2784.3 3.0267 5.8892 60.0;
70.0 285.9 1.3513 0.02737 1257.6 2580.5 1267.0 1505.1 2772.1 3.1211 5.8133 70.0;
80.0 295.1 1.3842 0.02352 1305.6 2569.8 1316.6 1441.3 2758.0 3.2068 5.7432 80.0;
90.0 303.4 1.4178 0.02048 1350.5 2557.8 1363.3 1378.9 2742.1 3.2858 5.6772 90.0;
100. 311.1 1.4524 0.01803 1393.0 2544.4 1407.6 1317.1 2724.7 3.3596 5.6141 100;
110. 318.2 1.4886 0.01599 1433.7 2529.8 1450.1 1255.5 2705.6 3.4295 5.5527 110;
120. 324.8 1.5267 0.01426 1473.0 2513.7 1491.3 1193.6 2684.9 3.4962 5.4924 120.;
130. 330.9 1.5671 0.01278 1511.1 2496.1 1531.5 1130.7 2662.2 3.5606 5.4323 130.;
140. 336.8 1.6107 0.01149 1548.6 2476.8 1571.1 1066.5 2637.6 3.6232 5.3717 140.;
150. 342.2 1.6581 0.01034 1585.6 2455.5 1610.5 1000.0 2610.5 3.6848 5.3098 150.;
160. 347.4 1.7107 0.009306 1622.7 2431.7 1650.1 930.6 2580.6 3.7461 5.2455 160.;
170. 352.4 1.7702 0.008364 1660.2 2405.0 1690.3 856.9 2547.2 3.8079 5.1777 170.;
180. 357.1 1.8397 0.007489 1698.9 2374.3 1732.0 777.1 2509.1 3.8715 5.1044 180.;
190. 361.5 1.9243 0.006657 1739.9 2338.1 1776.5 688.0 2464.5 3.9388 5.0228 190.;
200. 365.8 2.036 0.005834 1785.6 2293.0 1826.3 583.4 2409.7 4.0139 4.9269 200.;
220.9 374.1 3.155 0.003155 2029.6 2029.6 2099.3 0 2099.3 4.4298 4.4298 220.9];
Table(:,12) = [];
Table(:,8) = [];

%Choose Menu
disp('This Program will retrieve the data based on your input value')
disp('Choose input data type: ')
disp('1. Pressure');
disp('2. Temperature');
disp('3. Specific Volume Sat. Liquid');
disp('4. Specific Volume Sat. Vapor');
disp('5. Internal Energy Sat. Liquid');
disp('6. Internal Energy Sat. Vapor');
disp('7. Enthalpy Sat. Liquid');
disp('8. Enthalpy Sat. Vapor');
disp('9. Entropy Sat. Liquid');
disp('10. Entropy Sat. Vapor');
choice = input('Choose from 1 to 10: ');
value = input('Please input value: ');

%Calculation
[r,c] = size(Table);
aval = 0;
for i = 1:r
    if value < Table(i,choice)
        aval = 2;
    elseif value > Table(i,choice)
        aval = 3;
    elseif value == Table(i,choice)
        aval = 1;
        row = i;
        break
    end
end
if aval == 1
    properties = Table(row,:);
elseif aval == 2
    for i = 1:10
        row = 1;
        properties(1,i) =  Table(row,i)+(Table(row+1,i)-Table(row,i))/(Table(row+1,choice)-Table(row,choice))*(value-Table(row,choice));
    end
elseif aval == 3
    for i = 1:10
        row = r-1;
        properties(1,i) =  Table(row,i)+(Table(row+1,i)-Table(row,i))/(Table(row+1,choice)-Table(row,choice))*(value-Table(row,choice));
    end
else
    for i = 1:r-1
        if (Table(i,choice)-value)*(Table(i+1,choice)-value) < 0
            row = i;
            for i = 1:10
                properties(1,i) =  Table(row,i)+(Table(row+1,i)-Table(row,i))/(Table(row+1,choice)-Table(row,choice))*(value-Table(row,choice));
            end
            break
        end
    end
end

%Printing
fprintf('\nProperties:\n')
fprintf('1. Pressure = %.10f bar\n', properties(1));
fprintf('2. Temperature = %.10f C\n', properties(2));
fprintf('3. Specific Volume Sat. Liquid = %.10f x 10^-3 m^3/kg\n', properties(3));
fprintf('4. Specific Volume Sat. Vapor = %.10f m^3/kg\n', properties(4));
fprintf('5. Internal Energy Sat. Liquid = %.10f kJ/kg\n', properties(5));
fprintf('6. Internal Energy Sat. Vapor = %.10f kJ/kg\n', properties(6));
fprintf('7. Enthalpy Sat. Liquid = %.10f kJ/kg\n', properties(7));
fprintf('8. Enthalpy Sat. Vapor = %.10f kJ/kg\n', properties(8));
fprintf('9. Entropy Sat. Liquid = %.10f kJ/kgK\n', properties(9));
fprintf('10. Entropy Sat. Vapor = %.10f kJ/kgK\n', properties(10));

[Walter Roberson]

What are some sample inputs, and what is the expected output, and what output are you seeing instead?

[Bradley Jason Teguh]

for pressure 22 it should be temp 217.04 specific volume liquid 1.185 specific volume vapor 0.092 internal energy liquid 927.508 internal energy vapor 2601.42 enthalpy liquid 930.118 enthalpy vapor 2800.94 entropy liquid 2.49 entropy vapor 6.308. And for the matlab

Properties:

1. Pressure = 22.0000000000 bar

2. Temperature = 7934.5600000000 C

3. Specific Volume Sat. Liquid = 3.6392000000 x 10^-3 m^3/kg

4. Specific Volume Sat. Vapor = -12110.1780000000 m^3/kg

5. Internal Energy Sat. Liquid = 33149.2900000000 kJ/kg

6. Internal Energy Sat. Vapor = 13175.6000000002 kJ/kg

7. Enthalpy Sat. Liquid = 33138.3200000000 kJ/kg

8. Enthalpy Sat. Vapor = 16828.4000000000 kJ/kg

9. Entropy Sat. Liquid = 108.4658000000 kJ/kgK

10. Entropy Sat. Vapor = -149.8570000000 kJ/kgK

Its totaly wrong compared to the manual calculation

Answer 1

[Chunru]

You can use interp to do the task, which produce the value you want:

clear
clc
Table = [0.04 28.96 1.0040 34.800 121.45 2415.2 121.46 2432.9 2554.4 0.4226 8.4746 0.04;
0.06 36.16 1.0064 23.739 151.53 2425.0 151.53 2415.9 2567.4 0.5210 8.3304 0.06;
0.08 41.51 1.0084 18.103 173.87 2432.2 173.88 2403.1 2577.0 0.5926 8.2287 0.08;
0.10 45.81 1.0102 14.674 191.82 2437.9 191.83 2392.8 2584.7 0.6493 8.1502 0.10;
0.20 60.06 1.0172 7.649 251.38 2456.7 251.40 2358.3 2609.7 0.8320 7.9085 0.20;
0.30 69.10 1.0223 5.229 289.20 2468.4 289.23 2336.1 2625.3 0.9439 7.7686 0.30;
0.40 75.87 1.0265 3.993 317.53 2477.0 317.58 2319.2 2636.8 1.0259 7.6700 0.40;
0.50 81.33 1.0300 3.240 340.44 2483.9 340.49 2305.4 2645.9 1.0910 7.5939 0.50;
0.60 85.94 1.0331 2.732 359.79 2489.6 359.86 2293.6 2653.5 1.1453 7.5320 0.60;
0.70 89.95 1.0360 2.365 376.63 2494.5 376.70 2283.3 2660.0 1.1919 7.4797 0.70;
0.80 93.50 1.0380 2.087 391.58 2498.8 391.66 2274.1 2665.8 1.2329 7.4346 0.80;
0.90 96.71 1.0410 1.869 405.06 2502.6 405.15 2265.7 2670.9 1.2695 7.3949 0.90;
1.00 99.63 1.0432 1.694 417.36 2506.1 417.46 2258.0 2675.5 1.3026 7.3594 1.00;
1.50 111.4 1.0528 1.159 466.94 2519.7 467.11 2226.5 2693.6 1.4336 7.2233 1.50;
2.00 120.2 1.0605 0.8857 504.49 2529.5 504.70 2201.9 2706.7 1.5301 7.1271 2.00;
2.50 127.4 1.0672 0.7187 535.10 2537.2 535.37 2181.5 2716.9 1.6072 7.0527 2.50;
3.00 133.6 1.0732 0.6058 561.15 2543.6 561.47 2163.8 2725.3 1.6718 6.9919 3.00;
3.50 138.9 1.0786 0.5243 583.95 2546.9 584.33 2148.1 2732.4 1.7275 6.9405 3.50;
4.00 143.6 1.0836 0.4625 604.31 2553.6 604.74 2133.8 2738.6 1.7766 6.8959 4.00;
4.50 147.9 1.0882 0.4140 622.25 2557.6 623.25 2120.7 2743.9 1.8207 6.8565 4.50;
5.00 151.9 1.0926 0.3749 639.68 2561.2 640.23 2108.5 2748.7 1.8607 6.8212 5.00;
6.00 158.9 1.1006 0.3157 669.90 2567.4 670.56 2086.3 2756.8 1.9312 6.7600 6.00;
7.00 165.0 1.1080 0.2729 696.44 2572.5 697.22 2066.3 2763.5 1.9922 6.7080 7.00;
8.00 170.4 1.1148 0.2404 720.22 2576.8 721.11 2048.0 2769.1 2.0462 6.6628 8.00;
9.00 175.4 1.1212 0.2150 741.83 2580.5 742.83 2031.1 2773.9 2.0946 6.6226 9.00;
10.0 179.9 1.1273 0.1944 761.68 2583.6 762.81 2015.3 2778.1 2.1387 6.5863 10.0;
15.0 198.3 1.1539 0.1318 843.16 2594.5 844.84 1947.3 2792.2 2.3150 6.4448 15.0;
20.0 212.4 1.1767 0.09963 906.44 2600.3 908.79 1890.7 2799.5 2.4474 6.3409 20.0;
25.0 224.0 1.1973 0.07998 959.11 2603.1 962.11 1841.0 2803.1 2.5547 6.2575 25.0;
30.0 233.9 1.2165 0.06668 1004.8 2604.1 1008.4 1795.7 2804.2 2.6457 6.1869 30.0;
35.0 242.6 1.2347 0.05707 1045.4 2603.7 1049.8 1753.7 2803.4 2.7253 6.1253 35.0;
40.0 250.4 1.2522 0.04978 1082.3 2602.3 1087.3 1714.1 2801.4 2.7964 6.0701 40.0;
45.0 257.5 1.2692 0.04406 1116.2 2600.1 1121.9 1676.4 2798.3 2.8610 6.0199 45.0;
50.0 264.0 1.2859 0.03944 1147.8 2597.1 1154.2 1640.1 2794.3 2.9202 5.9734 50.0;
60.0 275.6 1.3187 0.03244 1205.4 2589.7 1213.4 1571.0 2784.3 3.0267 5.8892 60.0;
70.0 285.9 1.3513 0.02737 1257.6 2580.5 1267.0 1505.1 2772.1 3.1211 5.8133 70.0;
80.0 295.1 1.3842 0.02352 1305.6 2569.8 1316.6 1441.3 2758.0 3.2068 5.7432 80.0;
90.0 303.4 1.4178 0.02048 1350.5 2557.8 1363.3 1378.9 2742.1 3.2858 5.6772 90.0;
100. 311.1 1.4524 0.01803 1393.0 2544.4 1407.6 1317.1 2724.7 3.3596 5.6141 100;
110. 318.2 1.4886 0.01599 1433.7 2529.8 1450.1 1255.5 2705.6 3.4295 5.5527 110;
120. 324.8 1.5267 0.01426 1473.0 2513.7 1491.3 1193.6 2684.9 3.4962 5.4924 120.;
130. 330.9 1.5671 0.01278 1511.1 2496.1 1531.5 1130.7 2662.2 3.5606 5.4323 130.;
140. 336.8 1.6107 0.01149 1548.6 2476.8 1571.1 1066.5 2637.6 3.6232 5.3717 140.;
150. 342.2 1.6581 0.01034 1585.6 2455.5 1610.5 1000.0 2610.5 3.6848 5.3098 150.;
160. 347.4 1.7107 0.009306 1622.7 2431.7 1650.1 930.6 2580.6 3.7461 5.2455 160.;
170. 352.4 1.7702 0.008364 1660.2 2405.0 1690.3 856.9 2547.2 3.8079 5.1777 170.;
180. 357.1 1.8397 0.007489 1698.9 2374.3 1732.0 777.1 2509.1 3.8715 5.1044 180.;
190. 361.5 1.9243 0.006657 1739.9 2338.1 1776.5 688.0 2464.5 3.9388 5.0228 190.;
200. 365.8 2.036 0.005834 1785.6 2293.0 1826.3 583.4 2409.7 4.0139 4.9269 200.;
220.9 374.1 3.155 0.003155 2029.6 2029.6 2099.3 0 2099.3 4.4298 4.4298 220.9];
Table(:,12) = [];
Table(:,8) = [];
%Choose Menu
choice = 1;
value = 22;
output = interp1(Table(:, choice), Table, value)

output = 1×10

1.0e+03 * 0.0220 0.2170 0.0012 0.0001 0.9275 2.6014 0.9301 2.8009 0.0025 0.0063

[Bradley Jason Teguh]

its incorrect

[Chunru]

This is what you mentioned in your original post. The code gives you the correct answer. Check it again!

for pressure 22 it should be temp 217.04 specific volume liquid 1.185 specific volume vapor 0.092 internal energy liquid 927.508 internal energy vapor 2601.42 enthalpy liquid 930.118 enthalpy vapor 2800.94 entropy liquid 2.49 entropy vapor 6.308.

[Bradley Jason Teguh]

okay but what i want was actually only need to put the number. I dont want to type interp1 and so on. Basically i want to give it to the people so they only need to run it.

[Stephen23]

"okay but what i want was actually only need to put the number. I dont want to type interp1 and so on. Basically i want to give it to the people so they only need to run it."

Of course, that is the intent of Chunru's answer: it replaces your buggy/incorrect code in your script with simpler, neater, more efficient code that returns the correct answer. And then people "only need to run it".

[Bradley Jason Teguh]

how about extrapolation ?

[Chunru]

doc interp1