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?