有如下原始數據x,y,它對應的曲線圖形爲:
-9552 |
-2036.81 |
-9328 |
-2025.62 |
-9168 |
-2014.43 |
-9024 |
-2003.25 |
-8928 |
-1992.06 |
-8800 |
-1980.87 |
-8688 |
-1969.68 |
-8592 |
-1958.49 |
-8496 |
-1947.3 |
-8416 |
-1936.11 |
-8336 |
-1924.93 |
-8240 |
-1913.74 |
-8112 |
-1902.55 |
-8016 |
-1891.36 |
-7920 |
-1880.17 |
-7824 |
-1868.98 |
-7744 |
-1857.8 |
-7648 |
-1846.61 |
-7552 |
-1835.42 |
-7472 |
-1824.23 |
-7392 |
-1813.04 |
-7328 |
-1801.85 |
-7248 |
-1790.66 |
-7136 |
-1779.48 |
-7072 |
-1768.29 |
-7008 |
-1757.1 |
-6944 |
-1745.91 |
-6896 |
-1734.72 |
-6848 |
-1723.53 |
-6752 |
-1712.34 |
-6688 |
-1701.16 |
-6592 |
-1689.97 |
-6512 |
-1678.78 |
-6400 |
-1667.59 |
-6288 |
-1656.4 |
-6192 |
-1645.21 |
-6096 |
-1634.02 |
-6016 |
-1622.84 |
-5920 |
-1611.65 |
-5840 |
-1600.46 |
-5744 |
-1589.27 |
-5664 |
-1578.08 |
-5568 |
-1566.89 |
-5504 |
-1555.7 |
-5440 |
-1544.52 |
-5360 |
-1533.33 |
-5280 |
-1522.14 |
-5168 |
-1510.95 |
-5088 |
-1499.76 |
-5024 |
-1488.57 |
-4960 |
-1477.39 |
-4896 |
-1466.2 |
-4848 |
-1455.01 |
-4800 |
-1443.82 |
-4720 |
-1432.63 |
-4656 |
-1421.44 |
-4592 |
-1410.25 |
-4512 |
-1399.07 |
-4448 |
-1387.88 |
-4400 |
-1376.69 |
-4336 |
-1365.5 |
-4304 |
-1354.31 |
-4272 |
-1343.12 |
-4208 |
-1331.93 |
-4144 |
-1320.75 |
-4096 |
-1309.56 |
-4048 |
-1298.37 |
-3984 |
-1287.18 |
-3952 |
-1275.99 |
-3888 |
-1264.8 |
-3824 |
-1253.61 |
-3776 |
-1242.43 |
-3712 |
-1231.24 |
-3680 |
-1220.05 |
-3632 |
-1208.86 |
-3584 |
-1197.67 |
-3504 |
-1186.48 |
-3456 |
-1175.3 |
-3408 |
-1164.11 |
-3360 |
-1152.92 |
-3328 |
-1141.73 |
-3296 |
-1130.54 |
-3264 |
-1119.35 |
-3200 |
-1108.16 |
-3152 |
-1096.98 |
-3120 |
-1085.79 |
-3072 |
-1074.6 |
-3024 |
-1063.41 |
-2992 |
-1052.22 |
-2928 |
-1041.03 |
-2880 |
-1029.84 |
-2832 |
-1018.66 |
-2816 |
-1007.47 |
-2768 |
-996.279 |
-2720 |
-985.09 |
-2688 |
-973.902 |
-2656 |
-962.713 |
-2624 |
-951.525 |
-2576 |
-940.336 |
-2544 |
-929.148 |
-2512 |
-917.959 |
-2480 |
-906.77 |
-2432 |
-895.582 |
-2416 |
-884.393 |
-2368 |
-873.205 |
-2336 |
-862.016 |
-2320 |
-850.828 |
-2272 |
-839.639 |
-2224 |
-828.451 |
-2192 |
-817.262 |
-2160 |
-806.074 |
-2144 |
-794.885 |
-2112 |
-783.697 |
-2080 |
-772.508 |
-2032 |
-761.32 |
-2000 |
-750.131 |
-1984 |
-738.943 |
-1952 |
-727.754 |
-1936 |
-716.566 |
-1904 |
-705.377 |
-1888 |
-694.189 |
-1856 |
-683 |
-1824 |
-671.811 |
-1792 |
-660.623 |
-1760 |
-649.434 |
-1744 |
-638.246 |
-1712 |
-627.057 |
-1696 |
-615.869 |
-1680 |
-604.68 |
-1648 |
-593.492 |
-1616 |
-582.303 |
-1584 |
-571.115 |
-1568 |
-559.926 |
-1552 |
-548.738 |
-1536 |
-537.549 |
-1504 |
-526.361 |
-1488 |
-515.172 |
-1472 |
-503.984 |
-1456 |
-492.795 |
-1440 |
-481.607 |
-1408 |
-470.418 |
-1392 |
-459.23 |
-1376 |
-448.041 |
-1344 |
-436.852 |
-1312 |
-425.664 |
-1296 |
-414.475 |
-1296 |
-403.287 |
-1248 |
-392.098 |
-1232 |
-380.91 |
-1216 |
-369.721 |
-1216 |
-358.533 |
-1184 |
-347.344 |
-1168 |
-336.156 |
-1136 |
-324.967 |
-1120 |
-313.779 |
-1104 |
-302.59 |
-1088 |
-291.402 |
-1072 |
-280.213 |
-1040 |
-269.025 |
-1024 |
-257.836 |
-1008 |
-246.648 |
-992 |
-235.459 |
-976 |
-224.27 |
-944 |
-213.082 |
-944 |
-201.893 |
-912 |
-190.705 |
-896 |
-179.516 |
-880 |
-168.328 |
-880 |
-157.139 |
-848 |
-145.951 |
-848 |
-134.762 |
-832 |
-123.574 |
-800 |
-112.385 |
-768 |
-101.197 |
-752 |
-90.0082 |
-752 |
-78.8197 |
-736 |
-67.6311 |
-704 |
-56.4426 |
-688 |
-45.2541 |
-656 |
-34.0656 |
-656 |
-22.877 |
-624 |
-11.6885 |
-608 |
-0.5 |
-608 |
10.68852 |
-576 |
21.87705 |
-560 |
33.06557 |
-544 |
44.2541 |
-528 |
55.44262 |
-528 |
66.63115 |
-496 |
77.81967 |
-464 |
89.0082 |
-448 |
100.1967 |
-432 |
111.3852 |
-416 |
122.5738 |
-400 |
133.7623 |
-384 |
144.9508 |
-352 |
156.1393 |
-336 |
167.3279 |
-320 |
178.5164 |
-304 |
189.7049 |
-272 |
200.8934 |
-256 |
212.082 |
-240 |
223.2705 |
-208 |
234.459 |
-208 |
245.6475 |
-192 |
256.8361 |
-160 |
268.0246 |
-128 |
279.2131 |
-112 |
290.4016 |
-96 |
301.5902 |
-80 |
312.7787 |
-48 |
323.9672 |
-32 |
335.1557 |
0 |
346.3443 |
32 |
357.5328 |
48 |
368.7213 |
80 |
379.9098 |
112 |
391.0984 |
128 |
402.2869 |
144 |
413.4754 |
176 |
424.6639 |
192 |
435.8525 |
208 |
447.041 |
240 |
458.2295 |
272 |
469.418 |
288 |
480.6066 |
320 |
491.7951 |
336 |
502.9836 |
368 |
514.1721 |
400 |
525.3607 |
416 |
536.5492 |
448 |
547.7377 |
480 |
558.9262 |
512 |
570.1148 |
544 |
581.3033 |
576 |
592.4918 |
608 |
603.6803 |
640 |
614.8689 |
656 |
626.0574 |
688 |
637.2459 |
720 |
648.4344 |
752 |
659.623 |
784 |
670.8115 |
816 |
682 |
848 |
693.1885 |
880 |
704.377 |
912 |
715.5656 |
944 |
726.7541 |
976 |
737.9426 |
1008 |
749.1311 |
1056 |
760.3197 |
1088 |
771.5082 |
1104 |
782.6967 |
1152 |
793.8852 |
1184 |
805.0738 |
1216 |
816.2623 |
1248 |
827.4508 |
1280 |
838.6393 |
1312 |
849.8279 |
1344 |
861.0164 |
1392 |
872.2049 |
1424 |
883.3934 |
1472 |
894.582 |
1504 |
905.7705 |
1552 |
916.959 |
1584 |
928.1475 |
1632 |
939.3361 |
1680 |
950.5246 |
1728 |
961.7131 |
1776 |
972.9016 |
1824 |
984.0902 |
1856 |
995.2787 |
1904 |
1006.467 |
1952 |
1017.656 |
2000 |
1028.844 |
2048 |
1040.033 |
2096 |
1051.221 |
2128 |
1062.41 |
2176 |
1073.598 |
2224 |
1084.787 |
2288 |
1095.975 |
2320 |
1107.164 |
2384 |
1118.352 |
2432 |
1129.541 |
2480 |
1140.73 |
2544 |
1151.918 |
2576 |
1163.107 |
2640 |
1174.295 |
2704 |
1185.484 |
2752 |
1196.672 |
2800 |
1207.861 |
2864 |
1219.049 |
2912 |
1230.238 |
2960 |
1241.426 |
3008 |
1252.615 |
3072 |
1263.803 |
3136 |
1274.992 |
3200 |
1286.18 |
3264 |
1297.369 |
3328 |
1308.557 |
3392 |
1319.746 |
3440 |
1330.934 |
3520 |
1342.123 |
3584 |
1353.311 |
3648 |
1364.5 |
3712 |
1375.689 |
3776 |
1386.877 |
3856 |
1398.066 |
3920 |
1409.254 |
3984 |
1420.443 |
4032 |
1431.631 |
4128 |
1442.82 |
4192 |
1454.008 |
4272 |
1465.197 |
4320 |
1476.385 |
4400 |
1487.574 |
4464 |
1498.762 |
4544 |
1509.951 |
4608 |
1521.139 |
4704 |
1532.328 |
4752 |
1543.516 |
4832 |
1554.705 |
4896 |
1565.893 |
4960 |
1577.082 |
5040 |
1588.27 |
5120 |
1599.459 |
5184 |
1610.648 |
5264 |
1621.836 |
5328 |
1633.025 |
5392 |
1644.213 |
5472 |
1655.402 |
5520 |
1666.59 |
5616 |
1677.779 |
5696 |
1688.967 |
5776 |
1700.156 |
5840 |
1711.344 |
5904 |
1722.533 |
6000 |
1733.721 |
6064 |
1744.91 |
6144 |
1756.098 |
6208 |
1767.287 |
6272 |
1778.475 |
6352 |
1789.664 |
6400 |
1800.852 |
6480 |
1812.041 |
6528 |
1823.23 |
6592 |
1834.418 |
6672 |
1845.607 |
6736 |
1856.795 |
6800 |
1867.984 |
6864 |
1879.172 |
6928 |
1890.361 |
6992 |
1901.549 |
7040 |
1912.738 |
7104 |
1923.926 |
7152 |
1935.115 |
7184 |
1946.303 |
7248 |
1957.492 |
7280 |
1968.68 |
7328 |
1979.869 |
7376 |
1991.057 |
7408 |
2002.246 |
7456 |
2013.434 |
7488 |
2024.623 |
7536 |
2035.811 |
7568 |
2047 |
如果想得到該曲線的函數表達式(多項式擬合的表達式),在Excel 自帶圖表工具中可以能過爲曲線加趨勢線方式實現:
選擇多項式,調整階數讓擬合後在結果與原始曲線儘量重合,並勾選顯示公式:
EXCEL趨勢曲線多項式最高的階數是6階,但是實際效果與原始數據相差還是較大,看到是我們數據太複雜,EXCEL也無能爲力了,這時也只能請出強大的matlab來解決,把上述原始數據保存於EXCEL中,並強excel文件(.xls/xlsx)保存於matlab工作目錄下,然後運行如下代碼(可以把下面代碼保存爲.m文件,然後運行):
% 清屏,清除變量
clear,clc,close all
% 從excel中得到數據
x = xlsread('test.xlsx');
% 數據轉置
x = x';
% 畫出原始數據
plot(x(1,:),x(2,:),'r');
% 多項式擬合,如果擬合效果不好,可以得高多項式的階數,也就是下面最後一個參數,多項式越高,計算量就越大,
% P是多項式的表達式
[p,s]=polyfit(x(1,:),x(2,:),15); % 15是多項式階數
% 用上面擬合出的多項式計算對應的結果及與原始數據的偏差
[y_fit,DELTA]=polyval(p,x(1,:),s);
% 畫出擬合後的結果
hold on
plot(x(1,:),y_fit,'b');
% 給曲線加標註
legend('原始曲線','擬合後曲線');
% 顯示多項式各階係數
p
4階多項式擬合效果:
6階多項式擬合效果:
10階多項式擬合效果:
15階多項式擬合效果:
20階多項式擬合效果:
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