MATLAB基本指令

>> %MATLAB基本使用方法
>> %常见操作命令和快捷键
>> %clc清空命令窗口
>> %clear清除工作区中的变量
>> %clf清除图形窗口
>> x=-2*pi:0.05:2*pi;
>> y=3*sin(x)-2*cos(x);
>> plot(x,y)
>> clf
>> %disp显示变量
>> disp('极限是:')
极限是:
>> disp(x)
  1 至 9 列

   -6.2832   -6.2332   -6.1832   -6.1332   -6.0832   -6.0332   -5.9832   -5.9332   -5.8832

  10 至 18 列

   -5.8332   -5.7832   -5.7332   -5.6832   -5.6332   -5.5832   -5.5332   -5.4832   -5.4332

  19 至 27 列

   -5.3832   -5.3332   -5.2832   -5.2332   -5.1832   -5.1332   -5.0832   -5.0332   -4.9832

  28 至 36 列

   -4.9332   -4.8832   -4.8332   -4.7832   -4.7332   -4.6832   -4.6332   -4.5832   -4.5332

  37 至 45 列

   -4.4832   -4.4332   -4.3832   -4.3332   -4.2832   -4.2332   -4.1832   -4.1332   -4.0832

  46 至 54 列

   -4.0332   -3.9832   -3.9332   -3.8832   -3.8332   -3.7832   -3.7332   -3.6832   -3.6332

  55 至 63 列

   -3.5832   -3.5332   -3.4832   -3.4332   -3.3832   -3.3332   -3.2832   -3.2332   -3.1832

  64 至 72 列

   -3.1332   -3.0832   -3.0332   -2.9832   -2.9332   -2.8832   -2.8332   -2.7832   -2.7332

  73 至 81 列

   -2.6832   -2.6332   -2.5832   -2.5332   -2.4832   -2.4332   -2.3832   -2.3332   -2.2832

  82 至 90 列

   -2.2332   -2.1832   -2.1332   -2.0832   -2.0332   -1.9832   -1.9332   -1.8832   -1.8332

  91 至 99 列

   -1.7832   -1.7332   -1.6832   -1.6332   -1.5832   -1.5332   -1.4832   -1.4332   -1.3832

  100 至 108 列

   -1.3332   -1.2832   -1.2332   -1.1832   -1.1332   -1.0832   -1.0332   -0.9832   -0.9332

  109 至 117 列

   -0.8832   -0.8332   -0.7832   -0.7332   -0.6832   -0.6332   -0.5832   -0.5332   -0.4832

  118 至 126 列

   -0.4332   -0.3832   -0.3332   -0.2832   -0.2332   -0.1832   -0.1332   -0.0832   -0.0332

  127 至 135 列

    0.0168    0.0668    0.1168    0.1668    0.2168    0.2668    0.3168    0.3668    0.4168

  136 至 144 列

    0.4668    0.5168    0.5668    0.6168    0.6668    0.7168    0.7668    0.8168    0.8668

  145 至 153 列

    0.9168    0.9668    1.0168    1.0668    1.1168    1.1668    1.2168    1.2668    1.3168

  154 至 162 列

    1.3668    1.4168    1.4668    1.5168    1.5668    1.6168    1.6668    1.7168    1.7668

  163 至 171 列

    1.8168    1.8668    1.9168    1.9668    2.0168    2.0668    2.1168    2.1668    2.2168

  172 至 180 列

    2.2668    2.3168    2.3668    2.4168    2.4668    2.5168    2.5668    2.6168    2.6668

  181 至 189 列

    2.7168    2.7668    2.8168    2.8668    2.9168    2.9668    3.0168    3.0668    3.1168

  190 至 198 列

    3.1668    3.2168    3.2668    3.3168    3.3668    3.4168    3.4668    3.5168    3.5668

  199 至 207 列

    3.6168    3.6668    3.7168    3.7668    3.8168    3.8668    3.9168    3.9668    4.0168

  208 至 216 列

    4.0668    4.1168    4.1668    4.2168    4.2668    4.3168    4.3668    4.4168    4.4668

  217 至 225 列

    4.5168    4.5668    4.6168    4.6668    4.7168    4.7668    4.8168    4.8668    4.9168

  226 至 234 列

    4.9668    5.0168    5.0668    5.1168    5.1668    5.2168    5.2668    5.3168    5.3668

  235 至 243 列

    5.4168    5.4668    5.5168    5.5668    5.6168    5.6668    5.7168    5.7668    5.8168

  244 至 252 列

    5.8668    5.9168    5.9668    6.0168    6.0668    6.1168    6.1668    6.2168    6.2668

>> %hold 图形保持命令
>> %当关掉MATLAB时，定义的变量会被清除
>> %save 保持内存变量
>> bengS
>> save('bengS.mat')
>> %这时在文件夹会产生一个变量文件bengS.mat
>> %load 加载指定文件中的变量
>> load('bengS.mat')


>> %快捷键
>> %Ctrl+p
>> %Ctrl+p调用上一行
>> %Ctrl+f调用下一行
>> %MATLAB默认的数据类型是双精度型
>> x=5.7

x =

    5.7000

>> %整数数据类型:有符号整数(int8,int16,int32,int64),无符号整数(uint8,uint16,uint32,uint64)

>> a=uint8(56)

a =

   56

>> a=uint8(560)

a =

  255
>> %8位最大也就是2^8-1=255

>> a=uint16(560)

a =

    560

>> b=int8(-560)

b =

 -128

>> %参见C语言中截断

>> b=int16(-560)

b =

   -560

>> b=uint16(-560)

b =

      0
>>%类型不匹配，输出错误

>> A=uint16(magic(6))

A =

     35      1      6     26     19     24
      3     32      7     21     23     25
     31      9      2     22     27     20
      8     28     33     17     10     15
     30      5     34     12     14     16
      4     36     29     13     18     11

>> %浮点数；单精度浮点数(single)、双精度浮点数(double)
>> B=single(magic(6))

B =

    35     1     6    26    19    24
     3    32     7    21    23    25
    31     9     2    22    27    20
     8    28    33    17    10    15
    30     5    34    12    14    16
     4    36    29    13    18    11

>> %复数
>> sqrt(-1)

ans =

   0.0000 + 1.0000i

>> x=5+6i

x =

   5.0000 + 6.0000i

>> y=complex(0,1)

y =

   0.0000 + 1.0000i

>> xr=real(x)

xr =

     5
 
>> xi=imag(x)

xi =

     6

>> xabs=abs(x)

xabs =

    7.8102
 
>> sqrt(25+36)

ans =

    7.8102

>> %幅角
>> xa=angle(x)

xa =

    0.8761

>> %弧度-->角度
>> 180/pi*xa

ans =

   50.1944

>> %角度
>> conj(x)

ans =

   5.0000 - 6.0000i

>> xc=conj(x)

xc =

   5.0000 - 6.0000i


>> x = 0:0.01:2*pi;
>> y=x+i*x*sin(x);
错误使用  * 
内部矩阵维度必须一致。
 
>> a=[1,2,3];
>> b=[4,5,6];
>> c=a*b
错误使用  * 
内部矩阵维度必须一致。
 
>> c=a.*b

c =

     4    10    18

>> %点乘.*
>> y=x+i*x.*sin(x)

y =

  1 至 11 列

         0    0.0122    0.0288    0.0498    0.0752    0.1050    0.1392    0.1777    0.2206    0.2680    0.3196

  12 至 22 列

    0.3757    0.4360    0.5008    0.5698    0.6431    0.7208    0.8027    0.8890    0.9794    1.0741    1.1731

  23 至 33 列

    1.2762    1.3836    1.4951    1.6107    1.7305    1.8544    1.9824    2.1144    2.2504    2.3905    2.5345

  34 至 44 列

    2.6826    2.8345    2.9903    3.1500    3.3135    3.4809    3.6520    3.8269    4.0055    4.1877    4.3736

  45 至 55 列

    4.5631    4.7562    4.9528    5.1528    5.3564    5.5633    5.7737    5.9873    6.2043    6.4245    6.6479

  56 至 66 列

    6.8745    7.1042    7.3370    7.5728    7.8116    8.0533    8.2979    8.5453    8.7955    9.0485    9.3042

  67 至 77 列

    9.5625    9.8233   10.0867   10.3526   10.6210   10.8916   11.1647   11.4399   11.7174   11.9970   12.2788

  78 至 88 列

   12.5625   12.8483   13.1359   13.4255   13.7168   14.0099   14.3046   14.6010   14.8989   15.1984   15.4993

  89 至 99 列

   15.8015   16.1051   16.4099   16.7159   17.0230   17.3311   17.6403   17.9504   18.2613   18.5731   18.8855

  100 至 110 列

   19.1986   19.5124   19.8266   20.1413   20.4564   20.7718   21.0875   21.4033   21.7193   22.0353   22.3513

  111 至 121 列

   22.6672   22.9830   23.2985   23.6137   23.9285   24.2429   24.5568   24.8701   25.1828   25.4947   25.8058

  122 至 132 列

   26.1161   26.4254   26.7337   27.0410   27.3471   27.6519   27.9555   28.2577   28.5585   28.8578   29.1555

  133 至 143 列

   29.4515   29.7458   30.0383   30.3290   30.6177   30.9044   31.1891   31.4716   31.7519   32.0298   32.3055

  144 至 154 列

   32.5787   32.8494   33.1175   33.3831   33.6459   33.9059   34.1631   34.4173   34.6686   34.9169   35.1620

  155 至 165 列

   35.4039   35.6426   35.8780   36.1100   36.3385   36.5636   36.7850   37.0028   37.2169   37.4272   37.6336

  166 至 176 列

   37.8362   38.0348   38.2294   38.4198   38.6062   38.7883   38.9661   39.1396   39.3087   39.4733   39.6335

  177 至 187 列

   39.7890   39.9399   40.0862   40.2277   40.3644   40.4962   40.6231   40.7451   40.8620   40.9739   41.0806

  188 至 198 列

   41.1822   41.2786   41.3696   41.4553   41.5357   41.6106   41.6801   41.7440   41.8024   41.8551   41.9022

  199 至 209 列

   41.9436   41.9792   42.0091   42.0331   42.0512   42.0635   42.0698   42.0700   42.0643   42.0525   42.0346

  210 至 220 列

   42.0105   41.9803   41.9438   41.9011   41.8522   41.7969   41.7353   41.6673   41.5930   41.5122   41.4249

  221 至 231 列

   41.3312   41.2310   41.1243   41.0110   40.8911   40.7646   40.6315   40.4918   40.3455   40.1924   40.0327

  232 至 242 列

   39.8662   39.6931   39.5132   39.3266   39.1332   38.9330   38.7261   38.5123   38.2918   38.0645   37.8303

  243 至 253 列

   37.5893   37.3416   37.0870   36.8255   36.5573   36.2822   36.0003   35.7115   35.4160   35.1136   34.8044

  254 至 264 列

   34.4884   34.1656   33.8361   33.4997   33.1566   32.8067   32.4500   32.0867   31.7166   31.3398   30.9563

  265 至 275 列

   30.5662   30.1694   29.7660   29.3559   28.9393   28.5161   28.0864   27.6501   27.2074   26.7582   26.3025

  276 至 286 列

   25.8405   25.3721   24.8973   24.4162   23.9289   23.4353   22.9355   22.4295   21.9174   21.3991   20.8749

  287 至 297 列

   20.3446   19.8083   19.2661   18.7180   18.1641   17.6044   17.0389   16.4677   15.8909   15.3084   14.7204

  298 至 308 列

   14.1269   13.5280   12.9236   12.3139   11.6989   11.0787   10.4533    9.8228    9.1873    8.5467    7.9012

  309 至 319 列

    7.2509    6.5957    5.9358    5.2712    4.6020    3.9283    3.2500    2.5674    1.8804    1.1891    0.4937

  320 至 330 列

   -0.2059   -0.9095   -1.6172   -2.3287   -3.0440   -3.7632   -4.4860   -5.2123   -5.9423   -6.6756   -7.4123

  331 至 341 列

   -8.1523   -8.8955   -9.6419  -10.3912  -11.1435  -11.8987  -12.6566  -13.4173  -14.1805  -14.9463  -15.7145

  342 至 352 列

  -16.4850  -17.2578  -18.0328  -18.8098  -19.5888  -20.3697  -21.1524  -21.9368  -22.7228  -23.5103  -24.2992

  353 至 363 列

  -25.0895  -25.8810  -26.6736  -27.4673  -28.2619  -29.0573  -29.8535  -30.6503  -31.4476  -32.2454  -33.0435

  364 至 374 列

  -33.8419  -34.6404  -35.4390  -36.2374  -37.0358  -37.8338  -38.6315  -39.4287  -40.2253  -41.0212  -41.8163

  375 至 385 列

  -42.6106  -43.4038  -44.1959  -44.9869  -45.7765  -46.5647  -47.3513  -48.1363  -48.9196  -49.7011  -50.4805

  386 至 396 列

  -51.2579  -52.0332  -52.8062  -53.5767  -54.3448  -55.1103  -55.8731  -56.6331  -57.3901  -58.1442  -58.8950

  397 至 407 列

  -59.6427  -60.3870  -61.1278  -61.8650  -62.5986  -63.3284  -64.0543  -64.7762  -65.4940  -66.2076  -66.9169

  408 至 418 列

  -67.6217  -68.3220  -69.0177  -69.7086  -70.3947  -71.0758  -71.7518  -72.4227  -73.0883  -73.7485  -74.4033

  419 至 429 列

  -75.0525  -75.6959  -76.3336  -76.9654  -77.5912  -78.2109  -78.8243  -79.4315  -80.0323  -80.6265  -81.2142

  430 至 440 列

  -81.7951  -82.3693  -82.9365  -83.4968  -84.0499  -84.5959  -85.1345  -85.6658  -86.1896  -86.7058  -87.2143

  441 至 451 列

  -87.7151  -88.2080  -88.6929  -89.1699  -89.6386  -90.0992  -90.5514  -90.9953  -91.4306  -91.8574  -92.2755

  452 至 462 列

  -92.6848  -93.0854  -93.4770  -93.8596  -94.2331  -94.5974  -94.9525  -95.2983  -95.6347  -95.9615  -96.2788

  463 至 473 列

  -96.5865  -96.8845  -97.1727  -97.4510  -97.7193  -97.9777  -98.2260  -98.4641  -98.6921  -98.9097  -99.1170

  474 至 484 列

  -99.3139  -99.5003  -99.6761  -99.8413  -99.9959 -100.1397 -100.2728 -100.3950 -100.5063 -100.6066 -100.6959

  485 至 495 列

 -100.7742 -100.8413 -100.8973 -100.9420 -100.9755 -100.9976 -101.0084 -101.0078 -100.9957 -100.9721 -100.9370

  496 至 506 列

 -100.8902 -100.8319 -100.7619 -100.6803 -100.5868 -100.4817 -100.3647 -100.2359 -100.0953  -99.9427  -99.7783

  507 至 517 列

  -99.6019  -99.4135  -99.2132  -99.0008  -98.7764  -98.5400  -98.2915  -98.0309  -97.7582  -97.4734  -97.1764

  518 至 528 列

  -96.8674  -96.5461  -96.2128  -95.8672  -95.5095  -95.1396  -94.7576  -94.3633  -93.9569  -93.5384  -93.1076

  529 至 539 列

  -92.6647  -92.2096  -91.7424  -91.2630  -90.7715  -90.2679  -89.7521  -89.2243  -88.6844  -88.1325  -87.5685

  540 至 550 列

  -86.9924  -86.4044  -85.8044  -85.1925  -84.5686  -83.9329  -83.2853  -82.6258  -81.9546  -81.2716  -80.5768

  551 至 561 列

  -79.8704  -79.1523  -78.4226  -77.6813  -76.9285  -76.1642  -75.3884  -74.6013  -73.8028  -72.9931  -72.1720

  562 至 572 列

  -71.3398  -70.4965  -69.6421  -68.7766  -67.9002  -67.0129  -66.1148  -65.2059  -64.2862  -63.3560  -62.4151

  573 至 583 列

  -61.4637  -60.5019  -59.5298  -58.5473  -57.5546  -56.5518  -55.5389  -54.5160  -53.4832  -52.4406  -51.3883

  584 至 594 列

  -50.3263  -49.2547  -48.1736  -47.0832  -45.9834  -44.8744  -43.7563  -42.6292  -41.4931  -40.3482  -39.1946

  595 至 605 列

  -38.0323  -36.8615  -35.6822  -34.4946  -33.2988  -32.0948  -30.8828  -29.6630  -28.4353  -27.1999  -25.9569

  606 至 616 列

  -24.7065  -23.4487  -22.1836  -20.9114  -19.6323  -18.3462  -17.0534  -15.7539  -14.4479  -13.1354  -11.8167

  617 至 627 列

  -10.4919   -9.1610   -7.8242   -6.4816   -5.1334   -3.7797   -2.4205   -1.0561    0.3134    1.6879    3.0672

  628 至 629 列

    4.4513    5.8399


>> plot(x,y)
>> subplot(2,1,1)
>> %要画两行一列的第一个图
>> subplot(2,1,1)
>> plot(y)
>> title('直角坐标系绘图')
>> subplot(2,1,2)
>> theta=angle(y);
>> rho=abs(y);
>> polar(theta,rho)
>> title('极坐标系绘图')
>> %数据类型转换
>> %num2str将数字转换位字符串
>> %int2str mat2str str2double str3num cell2mat cell2struct cellstr mat2cell num2cell struct2cell 

>> a

a =

     1     2     3
>> isa(a,'int64')

ans =

     0

>> isa(a,'int32')

ans =

     0

>> isa(a,'double')

ans =

     1
>> str='I love you';
>> isa(str,'str')

ans =

     0

>> %数据类型操作函数
>> %isa（x,'type')
>> %判断是否为type指定的类型，是返回1，否则0
>> %cast(x,'type')
>> %设置x的类型为type
>> a

a =

     1     2     3

>> aa=cast(a,'uint8')

aa =

    1    2    3

>> isa(a,'double')

ans =

     1

>> isa(aa,'double')

ans =

     0

>> %aa不是double类型的

>> intmax('uint16')

ans =

  65535
 
>> realmax('double')

ans =

  1.7977e+308

>> realmin('double')

ans =

  2.2251e-308

>> intmax('int8')

ans =

  127

>> intmax('int16')

ans =

  32767

>> intmax('int32')

ans =

  2147483647

>> intmax('int64')

ans =

  9223372036854775807

>> %系统预定义的特殊变量
>> %ans pi eps 

>> x=0:1:2*pi;
>> sin(x)

ans =

         0    0.8415    0.9093    0.1411   -0.7568   -0.9589   -0.2794

>> x

x =

     0     1     2     3     4     5     6

>> cos(x)

ans =

    1.0000    0.5403   -0.4161   -0.9900   -0.6536    0.2837    0.9602

>> y1=sin(x)

y1 =

         0    0.8415    0.9093    0.1411   -0.7568   -0.9589   -0.2794

>> y2=cos(x)

y2 =

    1.0000    0.5403   -0.4161   -0.9900   -0.6536    0.2837    0.9602

>> pi

ans =

    3.1416

>> %圆周率前50位
 
>> vpa(pi,50)
 
ans =
 
3.1415926535897932384626433832795028841971693993751
 
>> vpa(pi)
 
ans =
 
3.1415926535897932384626433832795

>> vpa(pi,150)
 
ans =
 
3.14159265358979323846264338327950288419716939937510582097494459230781640628620899862803482534211706798214808651328230664709384460955058223172535940813
 
>> vpa(pi,1000)
 
ans =
 
3.141592653589793238462643383279502884197169399375105820974944592307816406286208998628034825342117067982148086513282306647093844609550582231725359408128481117450284102701938521105559644622948954930381964428810975665933446128475648233786783165271201909145648566923460348610454326648213393607260249141273724587006606315588174881520920962829254091715364367892590360011330530548820466521384146951941511609433057270365759591953092186117381932611793105118548074462379962749567351885752724891227938183011949129833673362440656643086021394946395224737190702179860943702770539217176293176752384674818467669405132000568127145263560827785771342757789609173637178721468440901224953430146549585371050792279689258923542019956112129021960864034418159813629774771309960518707211349999998372978049951059731732816096318595024459455346908302642522308253344685035261931188171010003137838752886587533208381420617177669147303598253490428755468731159562863882353787593751957781857780532171226806613001927876611195909216420199
 
>> %eps浮点数的精度，MATLAB中的最小数

>> eps

ans =

   2.2204e-16

>> inf

ans =

   Inf

>> nan

ans =

   NaN

>> %nan不定数
>> %inf无穷

>> %数据输出个数
>> %数据输出格式
>> %通过format命令指定
>> %format short long short_e long_e 
>> %默认format short
>> %四位小数
>> pi

ans =

    3.1416

>> format long
>> pi

ans =

   3.141592653589793

>> rand(5)

ans =

   0.814723686393179   0.097540404999410   0.157613081677548   0.141886338627215   0.655740699156587
   0.905791937075619   0.278498218867048   0.970592781760616   0.421761282626275   0.035711678574190
   0.126986816293506   0.546881519204984   0.957166948242946   0.915735525189067   0.849129305868777
   0.913375856139019   0.957506835434298   0.485375648722841   0.792207329559554   0.933993247757551
   0.632359246225410   0.964888535199277   0.800280468888800   0.959492426392903   0.678735154857773

>> format short
>> rand(5)

ans =

    0.7577    0.7060    0.8235    0.4387    0.4898
    0.7431    0.0318    0.6948    0.3816    0.4456
    0.3922    0.2769    0.3171    0.7655    0.6463
    0.6555    0.0462    0.9502    0.7952    0.7094
    0.1712    0.0971    0.0344    0.1869    0.7547