Skip to main content
P
ptc-13604881-Visitor
1-Visitor
January 27, 2010
Question

Solver ' D ' cannot be used in nonlinear diffequ.

  • January 27, 2010
  • 2 replies
  • 2827 views
Nonlinear Diffequ. are solvable with MathCad, or ?
Why Do I get the report "D" cannot be used here.
See attached worksheet.

2 replies

P
ptc-13682881-Visitor
1-Visitor
January 27, 2010
On 1/27/2010 5:41:24 AM, enricoaut wrote:
>Nonlinear Diffequ. are
>solvable with MathCad, or ?
>Why Do I get the report "D"
>cannot be used here.
>See attached worksheet.
____________________________

GENERALLY:

1. "Odesolve", solves non-linear DE's.
2. Finites differences does solve nicely.
3. Frobenius is applicable.
4. RK, RKFhelberg are applicable

HOWEVER ! ..........

1. Check for existing solutions: EQworld, CRC ...
2. Check for Lambert (W) solutions
3. Revisit the Mathsoft "Hires" example.
4. Checking the option for Radau/radau may be dramatic !

jmG
P
ptc-13604881-VisitorAuthor
1-Visitor
January 27, 2010
Sorry for the incorrect worksheet, here the better
one
S
StuartBruff23-Emerald V
23-Emerald V
January 27, 2010
On 1/27/2010 5:55:42 AM, enricoaut wrote:
== Nonlinear Diffequ. are solvable with MathCad, or ?
== Why Do I get the report "D" cannot be used here.

It's not a particularly helpful message. It looks like your numbers 'blow up' very quickly, suggesting there is a scaling factor or some other error in the function.

Try changing the time interval to 1 to see what I mean - there are values of the order of 10103 and 10191

Stuart
Terms & ConditionsAccessibility statement