       Re: problem with mathematica :(

• To: mathgroup at smc.vnet.net
• Subject: [mg98572] Re: problem with mathematica :(
• From: Szabolcs Horvát <szhorvat at gmail.com>
• Date: Mon, 13 Apr 2009 03:33:11 -0400 (EDT)
• References: <grs6c7\$qjg\$1@smc.vnet.net> <49E1AEC9.1090306@gmail.com>

```Szabolcs Horv=E1t wrote:
> olfa wrote:
>> Hi Mathematica community,
>> I have this system of equations:
>>  Reduce[{i >= iP, v + a*t/(1 - d) == vP + a*tP/(1 - d),
>>           t/d^(x/a) == tP/d^(xP/a), a*i + 1*x == a*iP + 1*xP,
>>           t/d^(i/-1) == tP/d^(iP/-1),
>>           z - c*x*(x - a)/(2*a) == zP - c*xP*(xP - a)/(2*a),iP===
0},
>> {iP,tP,vP,xP,zP},Backsubstitution->True]
>> But mathematica still in running until I abort.Could you tell me what
>> is the problem?
>
> Remove the inequality unless you really need it.  It makes the problem
> much much more difficult.
>

Actually it looks like you can re-add it once the equation part is solved=
:

Reduce[{v + (a t)/(1 - d) == vP + (a tP)/(1 - d),
t/d^(x/a) == tP/d^(xP/a), a i + 1 x == a iP + 1 xP,
t/d^(i/-1) == tP/d^(iP/-1),
z - (c x (x - a))/(2 a) == zP - (c xP (xP - a))/(2 a),
iP == 0}, {iP, tP, vP, xP, zP}, Backsubstitution -> True]

Reduce[% && i >= iP, {iP, tP, vP, xP, zP}, Reals]

```

• Prev by Date: Re: How to find current ViewAngle, ViewPoint during Rotating graphics?
• Next by Date: Re: How to find current ViewAngle, ViewPoint during Rotating graphics?
• Previous by thread: Re: problem with mathematica :(
• Next by thread: Re: problem with mathematica :(