1、符号运算系统MAPLE的使用(四）,七、微分方程（组）的求解,六、积分,六、积分,int.mws,Int(ln(t)/t,t);int(ln(t)/t,t); Int(x*sin(x),x)=int(x*sin(x),x); Int(sin(x)/x,x)=int(sin(x)/x,x); Int(exp(t)/t,t)=int(exp(t)/t,t);,不定积分,Int(exp(-x),x=a.b);int(exp(-x),x=a.b);I1:=Int(exp(-x2),x=0.1) =int(exp(-x2),x=0.1); ?erf evalf(I1); # 求近似值Int(sin(x)
2、/x,x=0.infinity)=int(sin(x)/x,x=0.infinity);Int(a*exp(b*x),x=0.d)=int(a*exp(b*x),x=0.d);,定积分,求下列积分,七 微分方程求解, ?dsolveode1:=t*diff(y(t),t) =y(t)*ln(t*y(t)-y(t); dsolve(ode1,y(t);ode2:=diff(y(t),t,t) +2*diff(y(t),t)+3*y(t)=a*sin(t); dsolve(ode2,y(t);,微分方程的初值问题求解, # solve the initial value problems of O
3、DE dsolve(ode1, y(1)=a,y(t); dsolve(ode2,y(0)=2,D(y)(0)=1,y(t);,微分方程组求通解, # solve the system of ODES sys1:= diff(y(t),t) =-x(t),diff(x(t),t)=y(t); dsolve(sys1, x(t),y(t);sys2 := diff(f(x),x) = cos(f(x), diff(g(x),x) = -f(x)(1/2), diff(h(x),x,x) = g(x)/f(x); dsolve(sys2, f,g,h);,微分方程组的初值问题求解, # solve the system of ODES with initial value conditions IC_1 := x(a)=A,y(b)=B; ans1 := dsolve(sys1 union IC_1,x(t),y(t); ans1 := combine(dsolve(sys1 union IC_1,x(t),y(t),trig); IC_2 := x(a)=A,diff(x(a),a)=B; ans2 := combine(dsolve(sys1 union IC_2,x(t),y(t),trig);,课堂练习,
