Frequently asked questions

• When I call SETUP, I get the error STO Error with 0 at level 1. Why?
  You did not use kermit to download files to your HP48 and your software is case-insensitive, or your filesystem is case-insensitive and translated uppercase names to lowercase names. Please use kermit, and unzip the Erable archive over a case-sensitive filesystem or a filesystem where filenames are uppercase names. MS-DOS should work, as well as ext2 (Linux), but not VFAT (Windows 9x filesystem under Linux).

• When I call INIT, I get the RCL Error: Undefined Name with GXKEYS at level 1 on the stack. Why?
  The reason is the same as above, but there is a simple workaround in this case. Type the following command line:
  'gxkeys' DUP RCL 'GXKEYS' STO PURGE INIT
  

• How can I launch the eqstk stack replacement?
  Type ASTK.

• ASTK does not launch eqstk. Why?
  If you want to shutdown your calc, you must press the right shift followed by the ON key. If you press the ON key too fast, this will stop eqstk unexpectedly and ASTK will not work.
  Workaround: type ON and C simultaneously, then again ASTK. If this doesn't work, you must reinstall eqstk.

• In previous versions of Erable, a CST menu was created. Is it gone?
  Yes, the user interface is now completely handled by the user key redefinition, because this is faster. You may create you own CST menu if you want by compiling the SCST file from the original package.

• How can I simplify $\sqrt{x^2}$?
  Type 28 SF to simplify $\sqrt{x^2}=\vert x\vert$. Otherwise $\sqrt{x^2}$ remains not modified. This flag setting is not the default because setting flag 28 means that subexpressions are always simplified and this slow down most simplifications.

• How can I simplify |x| if I know that x>0?
  Type 29 SF. If flag 29 is set, Erable will try to guess the sign of your expression: either at x=0⁺ or at $x=+\infty$ depending of the status of flag 24. The default is $x=+\infty$ but be aware that calling SERIES (directly or indirectly via LIMIT) sets flag 24 enabling guess at x=0⁺.

• Sometimes, Erable can not find the antiderivative of $\sin(x)$. Why?
  You are in complex mode. In this mode, RISCH does not recognize trigonometric functions, you must convert them to complex exponentials (EXPLN) or go back to real mode (13 CF).

• I have alg48 installed, I would like to use the factorization routines of alg48 inside Erable. Is it possible?
  Yes, but since I experienced many crashes, this feature is not included in the released versions. You can compile you own version and try different configurations to get this working. To do this, install the HP GNU tools and erablsrc.zip, uncompress it and uncomment in kernel.s and erable.s the lines between
  *teste la presence d'ALG48 and *fin de test ....
  Type compile to compile the whole package, download to your HP and test!