MATLAB练习例子八(函数处理)

function y = humps(x) y = 1./((x-0.3).^2 + 0.01) + 1./((x-0.9).^2 + 0.04) - 6; 》 fh = @humps; ??? fh = @ | 変数、または関数が見つかりません》 f = inline('1./((x-0.3).^2 + 0.01) + 1./((x-0.9).^2 + 0.04) - 6'); 》 f(2.0) ans = -4.8552 》 f = inline('y*sin(x)+x*cos(y)','x','y') f = Inline function: f(x,y) = y*sin(x)+x*cos(y) 》 f(pi,2*pi) ans = 3.1416 》 f = inline('1./((x-0.3).^2 + 0.01) + 1./((x-0.9).^2 + 0.04) - 6'); 》 fplot(f,[-5 5]) 》 grid on

》 fplot(inline('2*sin(x+3)'),[-1 1])

》 type humps.m function y = humps(x) y = 1./((x-0.3).^2 + 0.01) + 1./((x-0.9).^2 + 0.04) - 6; 》 fplot('humps',[-5 5])

》 fh = 'humps'; 》 feval(fh,2.0) ans = -4.8552 》》 fplot(inline('[2*sin(x+3), humps(x)]'),[-5 5])

求函数的最小参数值

》 x = fminbnd('humps',0.3,1) Optimization terminated successfully: the current x satisfies the termination criteria using OPTIONS.TolX of 1.000000e-004 x = 0.6370 》 x = fminbnd('humps',0.3,1,optimset('Display','iter')) Func-count x f(x) Procedure 1 0.567376 12.9098 initial 2 0.732624 13.7746 golden 3 0.465248 25.1714 golden 4 0.644416 11.2693 parabolic 5 0.6413 11.2583 parabolic 6 0.637618 11.2529 parabolic 7 0.636985 11.2528 parabolic 8 0.637019 11.2528 parabolic 9 0.637052 11.2528 parabolic Optimization terminated successfully: the current x satisfies the termination criteria using OPTIONS.TolX of 1.000000e-004 x = 0.6370 function b = three_var(v) x = v(1); y = v(2); z = v(3); b = x.^2 + 2.5*sin(y) - z^2*x^2*y^2; 》 v = [-0.6 -1.2 0.135]; 》 a = fminsearch('three_var',v) Optimization terminated successfully: the current x satisfies the termination criteria using OPTIONS.TolX of 1.000000e-004 and F(X) satisfies the convergence criteria using OPTIONS.TolFun of 1.000000e-004 a = 0.0000 -1.5708 0.1803

找零点

》 a = fzero('humps',-0.2) Zero found in the interval: [-0.10949, -0.264]. a = -0.1316 》 humps(a) ans = 8.8818e-016 》 humps(1) ans = 16 》 humps(-1) ans = -5.1378 》 options = optimset('Display','iter'); 》 a = fzero('humps',[-1 1],options) Func-count x f(x) Procedure 1 -1 -5.13779 initial 2 1 16 initial 3 -0.513876 -4.02235 interpolation 4 0.243062 71.6382 bisection 5 -0.473635 -3.83767 interpolation 6 -0.115287 0.414441 bisection 7 -0.150214 -0.423446 interpolation 8 -0.132562 -0.0226907 interpolation 9 -0.131666 -0.0011492 interpolation 10 -0.131618 1.88371e-007 interpolation 11 -0.131618 -2.7935e-011 interpolation 12 -0.131618 8.88178e-016 interpolation 13 -0.131618 -9.76996e-015 interpolation Zero found in the interval: [-1, 1]. a = -0.1316

数值积分

》 q = quad('humps',0,1) q = 29.8583 》 t = 0:0.1:3*pi; 》 plot3(sin(2*t),cos(t),t)

function f = hcurve(t) f = sqrt(4*cos(2*t).^2 + sin(t).^2 + 1); 》 len = quad('hcurve',0,3*pi) len = 17.2220 function out = integrnd(x,y) out = y*sin(t) + x*cos(y); 》 xmin = pi; 》 xmax = 2*pi; 》 ymin = 0; 》 ymax = pi; 》 result = dblquad('integrnd',xmin,xmax,ymin,ymax) ??? 't' は未定義の関数、または変数です. function out = integrnd(x,y) out = y*sin(x) + x*cos(y); 》 result = dblquad('integrnd',xmin,xmax,ymin,ymax) result = -9.8698