edgar

644 Reputation

11 Badges

14 years, 314 days

MaplePrimes Activity


These are answers submitted by edgar

According to Wikipedia, "d'Alembert's Test" is called "ratio test" in English. Try it on series sum(1/(2^n+3^n),n=1..infinity);
> f := x -> a*x^3+b*x^2+c*x+d; f := proc (x) options operator, arrow; a*x^3+b*x^2+c*x+d end proc > locmax_conditions := {f(-1)=-2,D(f)(-1)=0}; locmax_conditions := {3*a-2*b+c = 0, -a+b-c+d = -2} > locmin_conditions := {f(4)=4, D(f)(4)=0}; locmin_conditions := {48*a+8*b+c = 0, 64*a+16*b+4*c+d = 4} > solve(locmax_conditions union locmin_conditions); {a = -12/125, b = 54/125, c = 144/125, d = -172/125} > subs(%,f(x)); -(12/125)*x^3+(54/125)*x^2+(144/125)*x-172/125
And probably the professor wanted *him* to program it, rather than using some pre-programmed "lambda" function. --- G A Edgar
> solucion[1] := {x=2,y=3}; > solucion[2] := {x=3,y=4}; > solucion[3] := {x=2,y=0}; solucion[1] := {x = 2, y = 3} solucion[2] := {x = 3, y = 4} solucion[3] := {x = 2, y = 0} > for i from 1 to 3 do > x[i] := subs(solucion[i],x); > y[i] := subs(solucion[i],y); > end do; x[1] := 2 y[1] := 3 x[2] := 3 y[2] := 4 x[3] := 2 y[3] := 0 > x[2]; 3
]]How do I display the solutions it has when it says some may have been lost? I believe it first displays all the solutions it has, then it says "some solutions may have been lost" --- G A Edgar
Re(int(1/x,x)); ln(|x|) --- G A Edgar
plot([x^2/20,sin(x),2-x], x=0..5, color=[red,black,green]); If you live in Canada (or even if you don't) you can write colour for color. --- G A Edgar
# try everything up to 1000, if no result increase the bound for N from 1 to 1000 if irem(N,21)=19 then ...... end if; end for; --- G A Edgar
Maybe it would be better to use the regular int, rather than the inert substitute Int ?? It looks like just a polynomial in t, so after integration it should be much easier to work with, even if it has giant coefficients. --- G A Edgar
N. G. De Bruijn, "The Difference-Differential Equation F'(x) = e^(alpha*x+beta)*F(x-1)." Indagationes Math. 15 (1953) 449--464. If you write F(x) = e^(-x)*f(x), your equation becomes one of his. --- G A Edgar
Must be those pirates operating off Somalia. --- G A Edgar
It is hard to tell what you mean. Maybe give an example. Perhaps you need to increase the printlevel ... are your prints inside a loop or procedure? --- G A Edgar
f := (x,t)->t-x^3; f := proc (x, t) options operator, arrow; t-x^3 end proc f(x,t)=0; t-x^3 = 0 fsolve(f(x,t)=0,x); Error, (in fsolve) t is in the equation, and is not solved for g := unapply('fsolve(f(x,t)=0,x)',t); g := proc (t) options operator, arrow; fsolve(f(x, t) = 0, x) end proc g(0.2); .5848035476 evalf(Int(g,0..1)); .7500000000
Certain definite integrals of this kind are known... int(cos(a*sin(t)),t=0..Pi/2); (1/2)*Pi*BesselJ(0, a) --- G A Edgar
You want a closed-form solution? Why do you think there is one? Even this simplified equation is not solved by Maple: > de1 := diff(y(x),x) = 1/(y(x)-sin(x)); de1 := diff(y(x), x) = 1/(y(x)-sin(x)) > dsolve(de1,y(x)); > --- G A Edgar
4 5 6 7 8 9 Page 6 of 9