Re: DSolve bug in Mathematica version 4.1?,
- To: mathgroup at smc.vnet.net
- Subject: [mg27950] Re: [mg27924] DSolve bug in Mathematica version 4.1?,
- From: BobHanlon at aol.com
- Date: Sat, 24 Mar 2001 15:15:52 -0500 (EST)
- Sender: owner-wri-mathgroup at wolfram.com
Works on my Mac
$Version
4.1 for Power Macintosh (November 2, 2000)
a12 = 0.0124; a21 = 0.0111; a31 = 0.0039;
a13 = 0.000035; a41 = 0.0211; a42 = 0.0162;
inputPb = 49.3;
LeadFlowEqns = {x'[t] == -(a41 + a21 + a31) x[t] + a12 y[t] + a13 z[t] +
inputPb, y'[t] == a21 x[t] - (a42 + a12) y[t],
z'[t] == a31 x[t] - a13 z[t]};
DSolve[Join[LeadFlowEqns, {x[0] == 0, y[0] == 0, z[0] == 0}], {x[t], y[t],
z[t]}, t]
{{x[t] -> (3.1104718800634146*^-10*
(-2.314391202234146*^12*E^(0.02006624836527119*t) +
1.*E^(0.02009688059173561*t) - 0.0062134502923976605*
E^(0.040101864504077954*t) - 2.7497900381573*^12*
E^(0.04469938386119324*t) + 0.33164290935672514*
E^(0.044730016087657656*t) - 7.230340031250862*^11*
E^(0.06470436777353557*t) + 5.787215243515209*^12*
E^(0.06473499999999999*t) + 0.00044732344777960524*
E^(0.08473998391234233*t) - 0.0028326023391812864*
E^(0.08936813549592204*t) + 0.0007124783699972587*
E^(0.10937311940826437*t)))/E^(0.064735*t),
y[t] -> (-2.148397015844239*^-10*
(-2.314671420509761*^12*E^(0.02006624836527119*t) +
1.*E^(0.02009688059173561*t) - 0.005291705252017463*
E^(0.040101864504077954*t) + 5.159862487948824*^12*
E^(0.04469938386119324*t) - 0.6223706839529038*
E^(0.044730016087657656*t) + 4.067174537686742*^11*
E^(0.06470436777353557*t) - 3.2519085212081045*^12*
E^(0.06473499999999999*t) - 0.0009178447256581559*
E^(0.08473998391234233*t) - 0.0026458526260087316*
E^(0.08936813549592204*t) + 0.0006707649821404948*
E^(0.10937311940826437*t)))/E^(0.064735*t),
z[t] -> (-2.716760150178743*^-11*
(-2.315330354428725*^12*E^(0.02006624836527119*t) +
0.9999999999999999*E^(0.02009688059173561*t) -
0.007061592781482934*E^(0.040101864504077954*t) -
6.138973345570167*^12*E^(0.04469938386119324*t) +
0.7421210932391787*E^(0.044730016087657656*t) +
7.391595588243431*^15*E^(0.06470436777353557*t) -
7.383141284543434*^15*E^(0.06473499999999999*t) +
0.0047077285209886225*E^(0.08473998391234233*t) -
0.001307702366941284*E^(0.08936813549592204*t) -
0.0005230809467765136*E^(0.10937311940826437*t)))/
E^(0.064735*t)}}
Bob Hanlon
In a message dated 2001/3/24 1:17:13 AM, gsl at fab.enusa.es writes:
>I have check the System of Differential Eq. (from the book VisualDSolve
>by
>S.Wagon: ) that follow with different Math version.
>
>In vers 2.1 and 2.2 I obtain the fine solution.
>In vers. 3.0.0 don't work.
>In vers. 4.0 work using N[].
>In vers. 4.1 don`t work.
>
>Any suggestion to obtain the solution with Math 4.1 using DSolve (I know
>others way to solve the system)
>
>a12 = 0.0124; a21 = 0.0111; a31 = 0.0039; a13 = 0.000035; a41 = 0.0211;
>
>a42 = 0.0162; inputPb = 49.3;
>
>LeadFlowEqns = {x'[t] == -(a41 + a21 + a31) x[t] + a12 y[t] + a13 z[t]
>+
> inputPb, y'[t] == a21 x[t] - (a42 + a12) y[t],
> z'[t] == a31 x[t] - a13 z[t]};
>
>DSolve[Join[LeadFlowEqns, {x[0] == 0, y[0] == 0, z[0] == 0}], {x[t], y[t],
>
> z[t]}, t]
>
>In Math 4.1 I receive the message
>
>DSolve::"bvnul": "For some branches of the general solution, the given
>\boundary conditions lead to an empty solution."
>
>{ }
>