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1、实验名称：第三次上机实验目的：掌握符号表达式的生成与符号矩阵的创立，符号矩阵的简化符号代数方程的求解实验原理及实验内容：1、符号表达式的生成p64；符号矩阵的创立p68；符号矩阵的简化p73。2、符号代数方程求解。P793、求解：2cos(x)+y^(1/2)-ln(z)=72^x+2y-8z=-1x+y-cosh(z)=0编程练习：1、符号表达式的生成>>f='log(x)'f=log(x)>>eqation='a*x^2+b*x+c=0'eqation=a*x^2+b*x+c=0>>diffeg='Dy-y=x'diffeg=Dy-y=x2、符
2、号矩阵的创立>>a=sym('[1/sinx,sin(x)cos(x)^2/(b+x);9,exp(x^2+y^2),log(tanh(y))]')a=[1/sinx,sin(x),cos(x)^2/(b+x)][9,exp(x^2+y^2),log(tanh(y))]>>ms=['[1/s,sin(x)]';'[1,exp(x)]']ms=[1/s,sin(x)][1,exp(x)]>>b=[a;'[exp(-i),x^3+y^9]']>>b=[a;'[exp(-i),3,x^3+y^9]']b=[1/sinx,sin(x),cos(x)^2/(
3、b+x)][9,exp(x^2+y^2),log(tanh(y))][exp(-i),3,x^3+y^9]>>a=[2/3,sqrt(2),0.222;1.4,1/0.23,log(3)]a=0.66671.41420.22201.40004.34781.0986>>b=sym(a)b=[2/3,2^(1/2),111/500][7/5,100/23,2473854946935173/2251799813685248]3、符号矩阵的简化>>symsxy>>expand((x+1)^3)ans=x^3+3*x^2+3*x+1>>expand(sin(
4、x+y))ans=cos(x)*sin(y)+cos(y)*sin(x)>>symsxy;>>collect(x^2*y+y*x-x^2-2*x)ans=(y-1)*x^2+(y-2)*x>>symsx>>simplify(sin(x)^2+cos(x)^2)ans=1>>symscplahabeta>>simplify(exp(c*log(sqrt(alpha+beta))))ErrorusingalphaToomanyoutputarguments.>>symscalphabeta>>simplify(exp(c*log(sqrt(alpha+
5、beta))))ans=(alpha+beta)^(c/2)[n,d]=numden(x/y+y/x)n=x^2+y^2d=x*y>>horner(x^3-6*x^2+11*x-6)ans=x*(x*(x-6)+11)–64、符号代数方程求解>>[x,y,z]=solve('10*x-y=9','-x+10*y-2*z=7','-2*y+10*z=6')x=473/475y=91/95z=376/475>>vpa([x,y,z])ans=[0.99578947368421052631578947368421,0.957894736842105263
6、15789473684211,0.79157894736842105263157894736842]用fsolve求解functiony=exam3(x)y(1)=x(1)-0.7*sin(x(1))-0.2*cos(x(2));y(2)=x(2)-0.7*cos(x(1))+0.2*sin(x(2));y=[y(1)y(2)];>>x0=[0.50.5];>>fsolve('exam3',x0)ans=0.52650.50795、求解指定方程functionn=exam3_1(x)%UNTITLED3Summaryofthisfunctiongo
7、eshere%Detailedexplanationgoeshere%x(1)=x;x(2)=y;x(3)=z;n(1)=2*cos(x(1))+x(2)^(1/2)-log(x(3))-7;n(2)=2^x(1)+2*x(1)-8*x(3)+1;n(3)=x(1)+x(2)-cosh(x(3));n=[n(1)n(2)n(3)];end>>x0=[0.50.50.5];>>fsolve('exam3_1',x0)Nosolutionfound.fsolvestoppedbecausetherelativesizeofthecurrentstepi
8、slessthanthedefaultvalueofthestepsizetolerancesquared,butthev
