《MATLAB及應(yīng)用》實(shí)驗(yàn)指導(dǎo)書(shū)作業(yè)答案

1、?MATLAB 及及應(yīng)應(yīng)用用?實(shí)驗(yàn)實(shí)驗(yàn)指指導(dǎo)書(shū)導(dǎo)書(shū)班 級(jí)： 姓 名： 學(xué) 號(hào)： 總評(píng)成績(jī)： 汽車(chē)工程系電測(cè)與汽車(chē)數(shù)字應(yīng)用中心目錄目錄實(shí)驗(yàn)實(shí)驗(yàn) 04051001 MATLAB 語(yǔ)語(yǔ)言根底言根底 .3實(shí)驗(yàn)實(shí)驗(yàn) 04051002 MATLAB 科學(xué)計(jì)科學(xué)計(jì)算及算及繪圖繪圖.12實(shí)驗(yàn)實(shí)驗(yàn) 04051001 MATLAB 語(yǔ)語(yǔ)言根底言根底實(shí)驗(yàn)實(shí)驗(yàn)?zāi)康哪康?)熟悉 MATLAB 的運(yùn)行環(huán)境2)掌握 MATLAB 的矩陣和數(shù)組的運(yùn)算3)掌握 MATLAB 符號(hào)表達(dá)式的創(chuàng)立4)熟悉符號(hào)方程的求解實(shí)驗(yàn)實(shí)驗(yàn)內(nèi)容內(nèi)容任任選選 6 題題1.利用 rand 等函數(shù)產(chǎn)生以下矩陣：產(chǎn)生一個(gè)均勻分布在-5，5之間的隨機(jī)陣50

2、2，要求顯示精度為精確到小數(shù)點(diǎn)后一位精度控制指令為 format。format banka=-5; b=5; r = a + (b-a).* rand(50,2) r = 3.15 -2.24 4.06 1.80 -3.73 1.55 4.13 -3.37 1.32 -3.81 -4.02 -0.02 -2.22 4.60 0.47 -1.60 4.58 0.85 4.65 -2.76 -3.42 2.51 4.71 -2.45 4.57 0.06 -0.15 1.99 3.00 3.91 -3.58 4.59 -0.78 0.47 4.16 -3.61 2.92 -3.51 4.59 -2.

3、42 1.56 3.41 -4.64 -2.46 3.49 3.14 4.34 -2.56操作成績(jī)報(bào)告成績(jī) 1.79 4.29 2.58 -1.50 2.43 -3.03 -1.08 -2.49 1.55 1.16 -3.29 -0.27 2.06 -1.48 -4.68 3.31 -2.23 0.85 -4.54 0.50 -4.03 4.17 3.23 -2.14 1.95 2.57 -1.83 2.54 4.50 -1.20 -4.66 0.68 -0.61 -4.24 -1.18 -4.46 2.66 0.31 2.95 2.79 -3.13 4.34 -0.10 -3.70 -0.5

4、4 0.69 1.46 -0.31 2.09 -4.88 2.55 -1.63 2.在一個(gè)的測(cè)量矩陣 T100100中，刪除整行數(shù)據(jù)全為 0 的行，刪除整列數(shù)據(jù)全為 0 的列判斷某列元素是否為 0 方法：檢查 T(: , i) .* (T(: , i)是否為 0。T = rand(10,10);T(3,:) = 0;T(:,4) = 0;row,col = size(T);r = ; c = ;for i = row:-1:1if(sum(T(i,:).*T(i,:)=0) r(size(r)+1) = i;endendif(size(r)T(r,:) = ;endrow,col = size

5、(T);for j = col:-1:1if(sum(T(:,j).*T(:,j)=0) c(size(c)+1) = j;endendif(size(c)T(:,c) = end T = Columns 1 through 4 0.83 0.87 0.14 0.49 0.54 0.08 0.87 0.34 0.08 0.26 0.55 0.37 0.44 0.80 0.14 0.11 0.11 0.43 0.85 0.78 0.96 0.91 0.62 0.39 0.00 0.18 0.35 0.24 0.77 0.26 0.51 0.40 0.82 0.15 0.40 0.10 Colum

6、ns 5 through 8 0.13 0.17 0.18 0.31 0.94 0.65 0.37 0.51 0.58 0.65 0.78 0.82 0.06 0.45 0.08 0.79 0.23 0.55 0.93 0.64 0.35 0.30 0.78 0.38 0.82 0.74 0.49 0.81 0.02 0.19 0.44 0.53 0.04 0.69 0.45 0.35 Column 9 0.94 0.88 0.62 0.59 0.21 0.30 0.47 0.23 0.84 3.假設(shè)汽車(chē)系在以下各年度的人口統(tǒng)計(jì)如表所示類(lèi) 別年份大一新生學(xué)士畢業(yè)生200210282200312

7、0100200498942005105972006121110試用一個(gè)二維矩陣 STU 表示上述數(shù)據(jù)，并請(qǐng)計(jì)算出以下各數(shù)值：（1）汽車(chē)系在 20022006 年之間的每年平均新生、畢業(yè)生人數(shù)。（2）5 年來(lái)汽車(chē)系共有多少畢業(yè)生？（3）在哪幾年，新生數(shù)目比畢業(yè)生多？（4）5 年來(lái)每年的畢業(yè)生對(duì)新生的比例平均值為何？STU = 2002 102 82 2003 120 100 2004 98 94 2005 105 97 2006 121 110;Ave_Stu = round(mean(STU(:,2,3) Sum_gra = sum(STU(:,3)Ave_Stu = 109 97Sum_gr

8、a = 483 STU_radio = mean(STU(:,3)./STU(:,2) STU_radio = 0.8859 4.完成以下矩陣運(yùn)算：（1）使用 randn 產(chǎn)生一個(gè)1010的矩陣 A（2）計(jì)算 B=A+A/2。請(qǐng)注意，B 一定是一個(gè)對(duì)稱(chēng)矩陣（3）計(jì)算矩陣 B 的特征向量 e1 e2 e10使用函數(shù) eig（4）驗(yàn)證在 i 不等于 j 的情況下，ei和 ej的內(nèi)積必定為 0A=randn(10,10)B=(A+A)/2C=eig(B) A = Columns 1 through 6 0.5377 -1.3499 0.6715 0.8884 -0.1022 -0.8637 1.83

9、39 3.0349 -1.2075 -1.1471 -0.2414 0.0774 -2.2588 0.7254 0.7172 -1.0689 0.3192 -1.2141 0.8622 -0.0631 1.6302 -0.8095 0.3129 -1.1135 0.3188 0.7147 0.4889 -2.9443 -0.8649 -0.0068 -1.3077 -0.2050 1.0347 1.4384 -0.0301 1.5326 -0.4336 -0.1241 0.7269 0.3252 -0.1649 -0.7697 0.3426 1.4897 -0.3034 -0.7549 0.6

10、277 0.3714 3.5784 1.4090 0.2939 1.3703 1.0933 -0.2256 2.7694 1.4172 -0.7873 -1.7115 1.1093 1.1174 Columns 7 through 10 -1.0891 -0.6156 1.4193 -1.1480 0.0326 0.7481 0.2916 0.1049 0.5525 -0.1924 0.1978 0.7223 1.1006 0.8886 1.5877 2.5855 1.5442 -0.7648 -0.8045 -0.6669 0.0859 -1.4023 0.6966 0.1873 -1.49

11、16 -1.4224 0.8351 -0.0825 -0.7423 0.4882 -0.2437 -1.9330 -1.0616 -0.1774 0.2157 -0.4390 2.3505 -0.1961 -1.1658 -1.7947B = Columns 1 through 6 0.5377 0.2420 -0.7937 0.8753 0.1083 -1.0857 0.2420 3.0349 -0.2410 -0.6051 0.2366 -0.0638 -0.7937 -0.2410 0.7172 0.2807 0.4041 -0.0897 0.8753 -0.6051 0.2807 -0

12、.8095 -1.3157 0.1624 0.1083 0.2366 0.4041 -1.3157 -0.8649 -0.0185 -1.0857 -0.0638 -0.0897 0.1624 -0.0185 1.5326 -0.7613 -0.0458 0.6397 0.7129 0.6897 -0.3419 -0.1365 1.1189 -0.2479 0.0668 -0.0686 -0.5154 2.4989 0.8503 0.2458 1.4790 0.1444 0.2355 0.8107 0.7610 -0.0325 0.4370 0.2212 0.6523 Columns 7 th

13、rough 10 -0.7613 -0.1365 2.4989 0.8107 -0.0458 1.1189 0.8503 0.7610 0.6397 -0.2479 0.2458 -0.0325 0.7129 0.0668 1.4790 0.4370 0.6897 -0.0686 0.1444 0.2212 -0.3419 -0.5154 0.2355 0.6523 -1.4916 -1.0823 -0.1132 1.1340 -1.0823 0.4882 -0.2105 -1.0645 -0.1132 -0.2105 0.2157 -0.8024 1.1340 -1.0645 -0.8024

14、 -1.7947C = -4.0702 -3.4514 -1.5577 -1.2496 -0.0343 0.8496 1.4875 2.1549 3.2486 4.1882 5.以下 MATLAB 語(yǔ)句用于畫(huà)出函數(shù) 在 0, 10 的值。 x0.2e2)y(xx = 0:0.1:10; y = 2*exp(-0.2*x); plot(x, y); 利用 MATLAB 的 M-文件編輯器創(chuàng)立一個(gè)新的 M-文件，輸入上述代碼，保存為文件test1.m。然后在命令窗口中輸入 test1 執(zhí)行這個(gè)文件?？吹玫绞裁唇Y(jié)果？ x = 0:0.1:10; y = 2*exp(-0.2*x); plot(x,

15、y); 0123456789100.20.40.60.811.21.41.61.826.熟悉 MATALB 幫助的使用：1)通過(guò)以下兩種方式得到關(guān)于 exp 函數(shù)的幫助 （a）在命令窗口中輸入 help exp 命令；（b）運(yùn)用幫助空間窗口。2)使用 lookfor 命令查找出以 10 為底的對(duì)數(shù)函數(shù)，并計(jì)算 1、10、1000 的對(duì)數(shù)值。help exp EXP Exponential. EXP(X) is the exponential of the elements of X, e to the X. For complex Z=X+i*Y, EXP(Z) = EXP(X)*(COS(Y

16、)+i*SIN(Y). See also EXPM1, LOG, LOG10, EXPM, EXPINT. Overloaded methods: lti/exp codistributed/exp Reference page in Help browser doc exp lookfor log10 log10 - Common (base 10) logarithm. LOG10 Common (base 10) logarithm. LOG10(X) is the base 10 logarithm of the elements of X. Complex results are p

17、roduced if X is not positive. Class support for input X: float: double, single See also log, log2, exp, logm. Overloaded methods: codistributed/log10 Reference page in Help browser doc log10log10(1)log10(10)log10(1000) ans = 0ans = 1ans = 3 7.假設(shè) u=1 和 v=3，用 MATLAB 符號(hào)計(jì)算功能計(jì)算以下表達(dá)式的值：a. b.c.d.3v4u)vu/(2

18、v2)uv/(v3333/v42u = 1;v=3;a = 4*u/(3*v)b = 2*v(-2)/(u+v)c = v3/(v3-u3)d = 4*pi*v2/3 a = 0.4444b = 0.0556c = 1.0385d = 37.6991 8.a = 3, A = 4, b = a2, B = b2-1, c = a+A-2B, C = a+B+2c，求 C。使用符號(hào)函數(shù) solveS = solve(a-3,A-4,b-a2,B-b2+1,c-a-A+2*B,C-a-B-2*c);C=S.C C =-223 9.求解常微分方程 x=-x+x+1，x(0)=1，x(0)=0使用符號(hào)

19、函數(shù) dsolveS = dsolve(D2x=-Dx+x+1, Dx(0) = 1, x(0) = 0) S =(5(1/2)*exp(t*(5(1/2)/2 - 1/2)*(5(1/2) + 3)/10 + (5(1/2)*(5(1/2) - 3)/(10*exp(t*(5(1/2)/2 + 1/2) - 1 10.應(yīng)用 MATLAB 幫助窗口查找顯示當(dāng)前目錄的命令。a)MATLAB 啟動(dòng)時(shí)的當(dāng)前目錄是什么？ D:My DocumentsMATLABb)創(chuàng)立一個(gè)新的目錄 mynewdir，并將其改變?yōu)楫?dāng)前目錄。然后翻開(kāi) M-文件編輯窗口，增加以下語(yǔ)句： % create an input

20、array from -2*pi to 2*pit = -2*pi:pi/10:2*pi; % calculate|sin(t)| x=abs(sin(t); %plot result plot(t, x); 把此文件以 test2.m 為文件名保存，然后在命令窗口中輸入 test2 執(zhí)行此文件。 % create an input array from -2*pi to 2*pit = -2*pi:pi/10:2*pi; % calculate|sin(t)| x=abs(sin(t); %plot result plot(t, x); -8-6-4-20246800.10.20.30.40

21、.50.60.70.80.91c)關(guān)閉繪圖窗口，返回到原始目錄，然后在命令窗口中輸入 test2?？从泻吻闆r發(fā)生，為什么。? Undefined function or variable test2.因?yàn)?Matlab 命令窗口要執(zhí)行的 test2 已不存在于當(dāng)前目錄下思考思考題題1.MATLAB 中，數(shù)組與矩陣在表示與應(yīng)用上有哪些區(qū)別。二維數(shù)組相當(dāng)于矩陣，所以矩陣是數(shù)組的子集。數(shù)組運(yùn)算是指數(shù)組對(duì)應(yīng)元素之間的運(yùn)算,也稱(chēng)點(diǎn)運(yùn)算.矩陣的乘法、乘方和除法有特殊的數(shù)學(xué)含義，并不是數(shù)組對(duì)應(yīng)元素的運(yùn)算，所以數(shù)組乘法、乘方和除法的運(yùn)算符前特別加了一個(gè)點(diǎn)。矩陣是一個(gè)二維數(shù)組，所以矩陣的加、減、數(shù)乘等運(yùn)算與數(shù)組

22、運(yùn)算是一致的。但有兩點(diǎn)要注意：(1)對(duì)于乘法、乘方和除法等三種運(yùn)算，矩陣運(yùn)算與數(shù)組運(yùn)算的運(yùn)算符及含義都不同：矩陣運(yùn)算按線性變換定義，使用通常符號(hào)；數(shù)組運(yùn)算按對(duì)應(yīng)元素運(yùn)算定義，使用點(diǎn)運(yùn)算符；(2)數(shù)與矩陣加減、矩陣除法在數(shù)學(xué)是沒(méi)有意義的，在 MATLAB 中為簡(jiǎn)便起見(jiàn)，定義了這兩類(lèi)運(yùn)算 實(shí)驗(yàn)實(shí)驗(yàn) 04051002 MATLAB 科學(xué)科學(xué)計(jì)計(jì)算及算及繪圖繪圖實(shí)驗(yàn)實(shí)驗(yàn)?zāi)康哪康?)熟悉 MATLAB 所提供的常用數(shù)值計(jì)算的函數(shù)(方程組的求解、插值、擬合)；2)掌握 MATLAB 二維圖形繪制命令及其圖形控制plot、loglog、contour、polar 等；3)熟悉 MATLAB 三維圖形繪制命令

23、及其圖形控制(mesh、surf 等)。實(shí)驗(yàn)實(shí)驗(yàn)內(nèi)容內(nèi)容1.求 f(x) = 4x6-x+x3-95 在0，100上最大值、最小值，根。使用函數(shù)fminbnd、roots解法 1：yx1 = (x) 4*x6-x+x3-95;xn1, ymin1 = fminbnd (yx1, 0, 100);yx2 = (x) (4*x6-x+x3-95)*(-1);xn2, ymin2 = fminbnd (yx2, 0, 100);ymin = ymin1ymax = abs(ymin2)r = roots (4 0 0 1 0 -1 -95) ymin = -95.3258ymax = 4.0000e

24、+012r = 1.6860 0.8525 + 1.4852i 0.8525 - 1.4852i -1.7050 -0.8431 + 1.4514i -0.8431 - 1.4514i 解法 2：yx1 = (x) 4*x6-x+x3-95;xn1 = fminbnd (yx1, 0, 100);ymin = yx1(xn1)yx2 = (x) (4*x6-x+x3-95)*(-1);xn2 = fminbnd (yx2, 0, 100);ymax = abs(yx2(xn2)r = roots (4 0 0 1 0 -1 -95) 操作成績(jī)報(bào)告成績(jī)ymin = -95.3258ymax =

25、4.0000e+012r = 1.6860 0.8525 + 1.4852i 0.8525 - 1.4852i -1.7050 -0.8431 + 1.4514i -0.8431 - 1.4514i 2.請(qǐng)用梯形法、辛普森法分別計(jì)算積分值 trapz、quad1021dxxx采用 trapzformat longd = 0.01; x = 0 : d : 10;y = sqrt (x.2+x+1);Itrapz = d * trapz(x,y) Itrapz = 0.560524689738299 采用 quad 法一：采用匿名函數(shù)表達(dá)函數(shù)fx = (x)sqrt(x.2+x+1);Ic =

26、quad(fx,0,1) %Ic = quad(x)sqrt(x.2+x+1),0,1)Ic = 1.336907509306287 法二：采用字符串表達(dá)函數(shù)fx = sqrt(x.2+x+1);Ic = quad(fx,0,1) %Ic = quad(sqrt(x.2+x+1),0,1)Ic = 1.336907509306287 3.，用兩種方法求函數(shù)的根，并求其)/1(5)25. 1/()8 . 0()(323xxxxxxf極值與零點(diǎn)。yx=(x)x3+(x-0.8)2/(x+1.25)3-5*(x+1/x); xi1=fzero(yx,100) S=solve(x3+(x-0.8)2/

27、(x+1.25)3-5*(x+1/x),x); xi2=double(S) yx1=(x)(x3+(x-0.8)2/(x+1.25)3-5*(x+1/x)*(-1);x0,y0=fminbnd(yx,0,100);x1,y1=fminbnd(yx1,0,100); x0ymin=y0 x1ymax=abs(y1) xi1 = 2.42xi2 = 2.42 -0.78 -2.28 -0.03 -0.78 -0.03 -2.28x0 = 0.00ymin = -83384.32x1 = 100.00ymax = 999498.40 4.計(jì)算二重積分 使用函數(shù) dblquad 102022) 12(

28、dxdyyxxyyx法一：format long S1=dblquad(x,y)x.2 + y.2 + x*y + 2*x + y + 1,0,2,0,1)%采用匿名函數(shù)表示被積函數(shù)采用匿名函數(shù)表示被積函數(shù) S1 = 11.333333333333334 法二：format longS2=dblquad(x.2 + y.2 + x*y + 2*x + y + 1,0,2,0,1)%采用字符串表示被積函數(shù)采用字符串表示被積函數(shù) S2 = 11.333333333333334 法三：format longS3=dblquad(inline(x.2 + y.2 + x*y + 2*x + y + 1

29、),0,2,0,1)%采用內(nèi)聯(lián)對(duì)象表示被積函數(shù)采用內(nèi)聯(lián)對(duì)象表示被積函數(shù) S3 = 11.333333333333334 5.求解常微分方程 x=-x+x+1，x(0)=1，x(0)=0使用函數(shù) ode45，需建立 M 函數(shù)%function ydot = DyDt( t,y )%ydot = y(2);-y(2)+y(1)+1;tspan=0,30;y0=1;0;tt,yy=ode45(DyDt,tspan,y0);plot(tt,yy(:,1)xlabel(t),title(x(t) 051015202530024681012141618x 107tx(t)6.矩陣 M = 1, 2, 6;

30、 4, 2, 7; 8, 9, 3，求 M 的 LU 分解，QR 分解，對(duì)角陣，特征值分解。使用函數(shù) lu、qr、svd、eigM=1,2,6; 4,2,7; 8,9,3 L,U=lu(M) Q,R = qr(M) U,S,V = svd(M) V,D = eig(M) M = 1 2 6 4 2 7 8 9 3L = 0.125000000000000 -0.350000000000000 1.000000000000000 0.500000000000000 1.000000000000000 0 1.000000000000000 0 0U = 8.000000000000000 9.0

31、00000000000000 3.000000000000000 0 -2.500000000000000 5.500000000000000 0 0 7.550000000000001Q = -0.111111111111111 0.403623652610222 -0.908153218373000 -0.444444444444444 -0.837519079166211 -0.317853626430550 -0.888888888888889 0.368306583006828 0.272445965511900R = -9.000000000000000 -9.1111111111

32、11111 -6.444444444444446 0 2.446968393949471 -2.335971889481658 0 0 -6.856556798716150U = -0.340649406434347 0.570239995682372 0.747518781851062 -0.497549797795201 0.565277724377718 -0.657955388332905 -0.797748193736521 -0.596059931253995 0.091161273266672S = 14.733322466800640 0 0 0 6.6762727061857

33、98 0 0 0 1.535119487827004V = -0.591369269704128 -0.290151202937516 -0.752392627743998 -0.601095385785777 -0.463357935978190 0.651140353804830 -0.537556251974297 0.837324132340603 0.099607094945101V = -0.411139723734906 -0.771916546326007 -0.499195212370030 -0.548368659296601 0.623734541710148 -0.39

34、1426912299307 -0.728186748759158 0.122882329835336 0.773038881476651D = 14.294404543289518 0 0 0 -1.571214559240810 0 0 0 -6.723189984048725 7.a = 3, A = 4, b = a2, B = b2-1, c = a+A-2B, C = a+B+2c，求 C。S=solve(a-3,A-4,b-a2,B-b2+1,c-a-A+2*B,C-a-B-2*c);C=S.C C =-223 8.要求使用兩種方法求解建立矩陣 A、x、b，然后求解方程 Ax=b。

35、A = rand(4,4);b = rand(4,1);x1 = Abx2 = inv(A)*b x1 = -0.57 1.68 0.51 -1.09x2 = -0.57 1.68 0.51 -1.09 9.建立一個(gè) 55 矩陣，分別用 polyval 函數(shù)和 polyvalm 函數(shù)將矩陣代入函數(shù)f(x) = 1.35+0.0668x+0.436x2+0.695x3 ，計(jì)算出結(jié)果并比擬。M = rand (5,5);p = 0.695 0.436 0.0668 1.35; p1 = polyval (p,M) p2 = polyvalm (p,M) p1 = Columns 1 through

36、 3 1.416273310334431 1.577603661337243 1.940955656230394 1.815077991505921 2.430113845843678 1.406949363446819 1.776262021778414 1.450663147322607 1.585427932414832 1.375379839129871 1.677773869783320 1.847218105540334 1.365294117603149 1.394582397369172 2.247016005992466 Columns 4 through 5 2.42883

37、6296713937 2.127312503729469 1.630995247003777 1.406604568739067 1.369490026734659 2.068732353176615 1.372003373487775 1.402161453598795 1.407980403208802 2.346275520027405p2 = Columns 1 through 3 4.113590052495727 3.445384872329876 4.341731192204374 2.515775990534201 4.828757783598503 3.61019492469

38、7222 2.132717155051913 2.654470354135661 5.013810970658724 1.690556022812021 2.162871167325060 2.483223233864695 1.980889619250668 2.286972440952766 3.400444014658941 Columns 4 through 5 2.557533121548941 4.547439743592102 2.570185060288571 3.561897556465831 2.089627489618481 3.868086851403922 3.031

39、283580884611 2.610281181775873 1.809899463004465 5.088690311197585 10.t = an2 + bn，測(cè)得對(duì)應(yīng)數(shù)據(jù)如下：多項(xiàng)式插值 interp1，多項(xiàng)式擬合 polyfitt = 0, 20, 40, 60, 80, 100, 120, 140, 160, 183.5;n = 0, 1153, 2045, 2800, 3466, 4068, 4621, 5135, 5619, 6152;通過(guò)多項(xiàng)式擬合試求 a 和 b 的值。format bankt = 0,20,40,60,80,100,120,140,160,183.5;n

40、= 0,1153,2045,2800,3466,4068,4621,5135,5619,6152;t_n1500=interp1(n,t,1500)t_n4800=interp1(n,t,4800)p = polyfit(n, t,2)a=p(1)b=p(2) t_n1500 = 27.78t_n4800 = 126.96p = 0.00 0.01 0.05a = 0.00b = 0.01 11.北京內(nèi)燃機(jī)總廠生產(chǎn)的 492Q 發(fā)動(dòng)機(jī)，由試驗(yàn)測(cè)得的轉(zhuǎn)矩特性為：發(fā)動(dòng)機(jī)轉(zhuǎn)速 nrmin-110001500200025003000350038004000發(fā)動(dòng)機(jī)轉(zhuǎn)矩 TN m135.33147.101

41、52.98156.91147.10138.27133.37125.53試求出轉(zhuǎn)矩特性T = f(n)的多項(xiàng)式表示，并作出發(fā)動(dòng)機(jī)的外特性圖要有適當(dāng)?shù)臉?biāo)注。format bankn = 1000 1500 2000 2500 3000 3500 3800 4000;T = 135.33 147.10 152.98 156.91 147.10 138.27 133.37 125.53; p = polyfit (n, T, 4) Tn = poly2str (p,n) ni = 1000:10:4000;Ti = polyval (p,ni); plot (ni,Ti,n,T,o) ;title(f

42、ontsize15 colorblue 492Q 發(fā)動(dòng)發(fā)動(dòng)機(jī)外特性機(jī)外特性);xlabel(fontsize13 colorred 轉(zhuǎn)轉(zhuǎn)速速 n(r/min);ylabel(fontsize13 colorred 轉(zhuǎn)轉(zhuǎn)矩矩 T(N*m); grid onaxis onbox on Warning: Polynomial is badly conditioned. Add points with distinct X values, reduce the degree of the polynomial, or try centering and scaling as described in