东华大学matlab数学实验第四次答案

1、1>> p=1 1 1;x=roots(p)x = -0.5000 + 0.8660i -0.5000 - 0.8660i>> polyval(p,x)ans = 1.0e-15 * 0.3331 0.3331>> clear;>> p=3 0 -4 2 -1;x=roots(p)x = -1.4058 + 0.0000i 1.0000 + 0.0000i 0.2029 + 0.4427i 0.2029 - 0.4427i>> polyval(p,x)ans = 1.0e-13 * -0.2498 + 0.0000i -0.0266

2、+ 0.0000i 0.0000 + 0.0072i 0.0000 - 0.0072i>> clear;>> p=5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 -6 8 0 0 0 -5 0 0;x=roots(p)x = 0.0000 + 0.0000i 0.0000 + 0.0000i 0.9768 + 0.0000i 0.9388 + 0.2682i 0.9388 - 0.2682i 0.8554 + 0.5363i 0.8554 - 0.5363i 0.6615 + 0.8064i 0.6615 - 0.8064i 0.3516 + 0.987

3、8i 0.3516 - 0.9878i -0.0345 + 1.0150i -0.0345 - 1.0150i -0.4609 + 0.9458i -0.4609 - 0.9458i -0.1150 + 0.8340i -0.1150 - 0.8340i -0.7821 + 0.7376i -0.7821 - 0.7376i -0.9859 + 0.4106i -0.9859 - 0.4106i -1.0416 + 0.0000i -0.7927 + 0.0000i>> polyval(p,x)ans = 1.0e-12 * 0.0000 + 0.0000i 0.0000 + 0.

4、0000i 0.1305 + 0.0000i 0.0954 + 0.0245i 0.0954 - 0.0245i 0.0796 + 0.0419i 0.0796 - 0.0419i -0.0643 + 0.0680i -0.0643 - 0.0680i 0.1620 + 0.0550i 0.1620 - 0.0550i -0.0120 + 0.0557i -0.0120 - 0.0557i -0.0978 + 0.3836i -0.0978 - 0.3836i 0.0012 + 0.0121i 0.0012 - 0.0121i 0.0560 - 0.1047i 0.0560 + 0.1047i

5、 0.2392 + 0.0861i 0.2392 - 0.0861i -0.0636 + 0.0000i 0.0011 + 0.0000i>> p1=2 3;>> p2=conv(p1,p1);>> p=conv(p2,p1)p = 8 36 54 27>> p3=8 36 54 23;x=roots(p3)x = -1.8969 + 0.6874i -1.8969 - 0.6874i -0.7063 + 0.0000i>> polyval(p3,x)ans = 1.0e-13 * 0.1066 + 0.0799i 0.1066 -

6、0.0799i 0.0355 + 0.0000i>>2>> clear;>> fun= (x)(x*log(sqrt(x2-1)+x)-sqrt(x2-1)-x/2);>>fplot(fun,0,10) >> fzero(fun,2)ans = 2.11553>> fun= (x)7/10*sin(x(1)+2/10*cos(x(2)-x(1),7/10*cos(x(1)-2/10*sin(x(2)-x(2);>> x,f,h=fsolve(fun,0,0)Equation solved.fsolve comp

7、leted because the vector of function values is near zeroas measured by the default value of the function tolerance, andthe problem appears regular as measured by the gradient.<stopping criteria details>x = 0.5265 0.5079f = 1.0e-09 * -0.2859 -0.4618h = 1>>9(1)clear; >> xa=-2:1;ya=-7

8、:1;>> x,y=meshgrid(xa,ya);>> z=y.3/9+3*x.2.*y+9*x.2+y.2+x.*y+9;>> mesh(x,y,z) (2)>> clear;>> fun= (x)x(2).3/9+3*x(1).2.*x(2)+9*x(1).2+x(2).2+x(1).*x(2)+9;>> x,g=fminsearch(fun,0,0)x = 0 0g = 9>> fun= (x)-(x(2).3/9+3*x(1).2.*x(2)+9*x(1).2+x(2).2+x(1).*x(2)+9)

9、;>> x,g=fminsearch(fun,0,-6)x = -0.3333 -6.0000g = -22.000012>> clear;>> all=180*7500all = 1350000>> first=all*3/10first = 405000>> x=all*7/10x = 945000>> r=504/12/10000r = 0.0042>> n=20*12n = 240>> a=(1+r)n*r*x)/(1+r)n-1)a = 6.2575e+03>> x=x-100000x = 845000>> a=(1+r)n*r*x)/(1+r)n-1)a = 5.5953e+03>