## 49 Reputation

16 years, 231 days

## solve equations...

Maple

Hi I will appreciate some help

I am trying to find the algebraic solution of the equation and want to express z in terms of c

z1 := 819*z^6+(-396+396*c)*z^4+306*z^3*c+(63*c^2-126*c+63)*z^2+(90*c^2-90*c)*z+6*c^3-9*c^2+18*c-6;

i use solve(z1=0,z) but i got

[z=RootOf(273 _Z^6+(-132+132 c) _Z^4+102 _Z^3 c+(-42 c+21+21 c^2) _Z^2+(-30 c+30 c^2) _Z-2+2 c^3-3 c^2+6 c).

Can anyone help?

## algsubs...

Maple

Hi I 'm using algsubs and i want to substitute p=((m-b)/m) in the

expression

f:=((m-b)/m)^2m+b^2*m so that

i obtain

p^m+b^2*m;

When i use algsubs((m-b)/m)=p,f) it does simplify.

Then i use algsubs(m-b=m*p,f) i got p^m+(1-2*p+p^2)*m

i do not want the last part to be expressed in terms of p.

I will appreciate your help and suggestion.

Thanks

Rajiv

## simplify...

Maple
<p>Hi i m trying to simplify this expression:</p>
<p><maple>f:=e^p/(e^(2*p)+e^p)</maple></p>
<p>i use simplify, factor but it remains the same.</p>
<p>It should be 1/(e^p+1)</p>
<p>I will appreciate ypur help or any suggestions.</p>
<p>Thanks,</p>
<p>Rajiv</p>

## finding the Hessian (third order tensor)...

Maple
Hi I want to know whether it is possible to obtain the third order tensor (second derivative) and also the higher order derivatives in Maple just as we can find the Jacobian. Then how? For example, x=array(1..n): f:=[x[1]^2-2x[2], x[2]^3-3x[3]]: jac:=jacobian(f,x); we can get the jacobian. Can we get the second derivative (n by n by n matrix) and also the higher order derivatives. Thanks.

## plot vectors...

Maple
Hi I am getting a problem with plot. I am trying to plot ka (number of iterations) versus va (error norm) in this worksheet: > with(linalg):with(LinearAlgebra):with(plots):SOS:=proc(x) local n,k; n:=vecdim(x); sum(x[k]^2,k=1..n); end;NJ2Next:=proc(f,x,x0) local val,jac, xn, xn1, val1, val2; val:=eval(subs(x=x0,f)); jac:=eval(jacobian(f,x),x=x0):jac:=inverse(jac); xn:=evalm(x0-jac&*val); val1:=eval(subs(x=xn,f));xn1:=evalm(xn-jac&*val1); val2:=eval(subs(x=xn1,f)); evalm(xn1-jac&*val2); end: > NJ2:=proc(f,x,x0,N) local k, sol, valf, va, ka;sol:=array(0..N):sol[0]:=x0:va:=array(1..N):ka:=array(1..N):valf:=eval(subs(x=x0,f)): for k from 1 to N do sol[k]:=NJ2Next(f,x,sol[k-1]): valf:=eval(subs(x=sol[k-1],f)): va[k]:=evalm(log(norm(sol[k]-sol[k-1],2))):ka[k]:=eval(k):err:=evalm(norm(sol[k]-sol[k-1],2)): od: print(ka):print(va) :plot([ka,va]):end:
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