Axel Vogt schrieb:   
   >   
   > On 22.07.2016 22:31, clicliclic@freenet.de wrote:   
   > > clicliclic@freenet.de schrieb:   
   > ...   
   > > My detection of a bug may have been premature: Maple's arcsin(z) could   
   > > be defined differently from Derive's ASIN(z) = #i*LN(SQRT(1-z^2) -   
   > > #i*z), in which case Maple's result might in fact be correct for all   
   > > real a with |a| > 1, and perhaps even for all real a.   
   > >   
   > > I haven't tried to look Maple's definition up.   
   >   
   > maple := - I*ln( sqrt(1-z^2) + z*I );   
   > derive:=   I*ln( sqrt(1-z^2) - I*z );   
   >   
   > I think they are equal   
      
   Yes: Both LN arguments are limited to the closed right half-plane, and   
   (SQRT(1-z^2) + #i*z)*(SQRT(1-z^2) - #i*z) = 1.   
      
   Martin.   
      
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