Mathematica 9 is now available
Services & Resources / Wolfram Forums
-----
 /
MathGroup Archive
1996
*January
*February
*March
*April
*May
*June
*July
*August
*September
*October
*November
*December
*Archive Index
*Ask about this page
*Print this page
*Give us feedback
*Sign up for the Wolfram Insider

MathGroup Archive 1996

[Date Index] [Thread Index] [Author Index]

Search the Archive

Abs[] help please

  • To: mathgroup at smc.vnet.net
  • Subject: [mg5399] Abs[] help please
  • From: robpeterson at sprintmail.com (Rob Peterson)
  • Date: Thu, 5 Dec 1996 14:50:33 -0500
  • Organization: Sprint Internet Passport
  • Sender: owner-wri-mathgroup at wolfram.com

I may not understand the limitations of Abs[].

This works just fine:
s[L_]=I/(L+1/L);(* a complex function *)
Plot[Evaluate[D[Abs[s[L]],L]],{L,1,2}]
(*The Abs[] of a complex function, which is real, apparently has a
real derivative and it is plotted.*)


However, If I put another "I" in the function definition, the
derivative of the Abs[] appears to have an imaginary component:
s[L_]=I/(L+I/L);(* has I instead of 1 *)
Plot[Evaluate[D[Abs[s[L]],L]],{L,1,2}]

The error message is as follows
Plot::"plnr": (1 - I/L^2)* REAL "is not a mach. size real number".
For some reason a factor of (1-I/L^2) showed up (REAL is some real
function).

Can anyone give me a clue how I might be able to plot the derivative
of the Abs[] of this type of complex function?






  • Prev by Date: select a range of elements from a nested list
  • Next by Date: Re: A Bug in Parametric Plot ?
  • Previous by thread: Re: select a range of elements from a nested list
  • Next by thread: Re: Abs[] help please