Matlab学习笔记03

书籍：Matlab实用教程
工具：Matlab2021a

电脑信息：Intel® Xeon® CPU E5-2603 v3 @ 1.60GHz

系统类型：64位操作系统，基于X64的处理器 windows10 专业版

第2章 MATLAB数值计算

2.2 矩阵和数组
2.2.3 字符串

>>str1='Hello'str1='Hello'>>str2='I''m a chinese.'str2='I'm a chinese.'>>whos Name Size Bytes Class Attributes str11x510charstr21x1428char>>length(str1)ans=5>>x1=double(str1)x1=72101108108111>>x2=x1+1x2=73102109109112>>char(x1)ans='Hello'>>char(x2)ans='Ifmmp'>>class(str1)ans='char'>>class(x1)ans='double'>>ischar(str1)ans=logical1>>str3=[str1,str2]str3='HelloI'm a chinese.'>>str6=str2mat(str1,str2,str3)str6=3×19char数组'Hello ''I'm a chinese.''HelloI'm a chinese.'>>str7=strvcat(str1,str2)str7=2×14char数组'Hello ''I'm a chinese.'>>str8='a=2*5'str8='a=2*5'>>eval(str8)a=10>>disp(str1)Hello>>

2.2.4 矩阵和数组运算

>>A=[123;456;789]A=123456789>>det(A)ans=-9.5162e-16>>rank(A)ans=2>>inv(A)警告:矩阵接近奇异值，或者缩放错误。结果可能不准确。RCOND=2.202823e-18。 ans=1.0e+16*0.3153-0.63050.3153-0.63051.2610-0.63050.3153-0.63050.3153>>[v,d]=eig(A)v=-0.2320-0.78580.4082-0.5253-0.0868-0.8165-0.81870.61230.4082d=16.1168000-1.1168000-0.0000>>diag(A)ans=159>>[l,u]=lu(A)l=0.14291.000000.57140.50001.00001.000000u=7.00008.00009.000000.85711.714300-0.0000>>[q,r]=qr(A)q=-0.12310.90450.4082-0.49240.3015-0.8165-0.8616-0.30150.4082r=-8.1240-9.6011-11.078200.90451.809100-0.0000>>[u,s,v]=svd(A)u=-0.21480.88720.4082-0.52060.2496-0.8165-0.8263-0.38790.4082s=16.84810001.06840000.0000v=-0.4797-0.7767-0.4082-0.5724-0.07570.8165-0.66510.6253-0.4082>>x1=[12;34;56]x1=123456>>x2=eye(3,2)x2=100100>>x1+x2 ans=223556>>x1.*x2 ans=100400>>x1*x2 错误使用*用于矩阵乘法的维度不正确。请检查并确保第一个矩阵中的列数与第二个矩阵中的行数匹配。要执行按元素相乘，请使用'.*'。 相关文档>>x3=eye(2,3)x3=100010>>x1*x3 ans=120340560>>A=[2-13;31-5;4-11]A=2-1331-54-11>>B=[559]B=559>>B=[5;5;9]B=559>>X=A\B X=2.0000-1.00000.0000>>x1=[12;34]x1=1234>>x2=eye(2)x2=1001>>x1/x2 ans=1234>>inv(x1)ans=-2.00001.00001.5000-0.5000>>x1\x2 ans=-2.00001.00001.5000-0.5000>>x1./x2 ans=1Inf Inf4>>x1.\x2 ans=1.0000000.2500>>x1^2ans=7101522>>x1^-1ans=-2.00001.00001.5000-0.5000>>x1^0.2ans=0.8397+0.3672i0.2562-0.1679i0.3842-0.2519i1.2239+0.1152i>>2^x1 ans=10.482714.151921.227831.7106>>2.^x1 ans=24816>>x1.^x2 ans=1114>>x3=x1+x2*i x3=1.0000+1.0000i2.0000+0.0000i3.0000+0.0000i4.0000+1.0000i>>x3'ans=1.0000-1.0000i3.0000+0.0000i2.0000+0.0000i4.0000-1.0000i>>x3.' ans=1.0000+1.0000i3.0000+0.0000i2.0000+0.0000i4.0000+1.0000i>>t=linspace(0,2*pi,6)t=01.25662.51333.76995.02656.2832>>y=sin(t)y=00.95110.5878-0.5878-0.9511-0.0000>>y1=abs(y)y1=00.95110.58780.58780.95110.0000>>1-exp(-t).*y ans=1.00000.72930.95241.01361.00621.0000>>a=0;b=5;c=10;>>(a~=0)&&(b<c)ans=logical0>>(a~=0)||(b<c)ans=logical1>>t=linspace(0,3*pi);>>y=sin(t)y=列1至2600.09510.18930.28170.37170.45820.54060.61820.69010.75570.81460.86600.90960.94500.97180.98980.99890.99890.98980.97180.94500.90960.86600.81460.75570.6901列27至520.61820.54060.45820.37170.28170.18930.0951-0.0000-0.0951-0.1893-0.2817-0.3717-0.4582-0.5406-0.6182-0.6901-0.7557-0.8146-0.8660-0.9096-0.9450-0.9718-0.9898-0.9989-0.9989-0.9898列53至78-0.9718-0.9450-0.9096-0.8660-0.8146-0.7557-0.6901-0.6182-0.5406-0.4582-0.3717-0.2817-0.1893-0.09510.00000.09510.18930.28170.37170.45820.54060.61820.69010.75570.81460.8660列79至1000.90960.94500.97180.98980.99890.99890.98980.97180.94500.90960.86600.81460.75570.69010.61820.54060.45820.37170.28170.18930.09510.0000>>t1=(t<pi)|(t>2*pi)t1=1×100logical 数组 列1至66111111111111111111111111111111111000000000000000000000000000000000列67至1001111111111111111111111111111111111>>y1=t1.*y y1=列1至2600.09510.18930.28170.37170.45820.54060.61820.69010.75570.81460.86600.90960.94500.97180.98980.99890.99890.98980.97180.94500.90960.86600.81460.75570.6901列27至520.61820.54060.45820.37170.28170.18930.09510000000000000000000列53至78000000000000000.00000.09510.18930.28170.37170.45820.54060.61820.69010.75570.81460.8660列79至1000.90960.94500.97180.98980.99890.99890.98980.97180.94500.90960.86600.81460.75570.69010.61820.54060.45820.37170.28170.18930.09510.0000>>a=[1inf;02]a=1Inf02>>b=[01;10]b=0110>>all(a)ans=1×2logical 数组01>>any(a)ans=1×2logical 数组11>>isequal(a,b)ans=logical0>>isempty(a)ans=logical0>>isfinite(a)ans=2×2logical 数组1011>>isinf(a)ans=2×2logical 数组0100>>isnan(a)ans=2×2logical 数组0000>>isnumeric(a)ans=logical1>>isreal(a)ans=logical1>>isprime(b)ans=2×2logical 数组0000>>isspace(a)ans=2×2logical 数组0000>>find(b)ans=23>>