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    rpn28s Project Overview
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This project plans to create a clone of HP-28S calculator language,
including at least stack, store, branch, test, trig and logs commands.

Following objects are managed: scalars, symbols, strings, programs.

Notes:
- Under Linux x86_64, floating representation is 128-bit quadruple
  precision format. Thus precision is much better than HP28S.

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Here is a list of HP28s reserved words.
Some new commands are added. They are tagged with (+).

Already implemented commands are tagged with (*).

DBG
 verbose(*)(+)

STACK
 drop(*), swap(*), roll, dup(*), over, dup2(*), drop2(*), rot(*),
 list->, rolld, pick(*), dupn, dropn, depth(*), ->list

STORE
 sto(*), rcl(*), purge(*), sto+, sto-, sto*, sto/, sneg, sinv, sconj,
 erase(*)(+), vars(*)(+)

MEMORY
 mem, menu, order, path, home, crdir, vars, clusr

ALGEBRA
 neg(*)(+), colct, expan, size, form, obsub, exsub, taylr, isol, quad,
 show, obget, exget

STAT
 ∑dat, ∑par, ∑+, ∑-, n∑, cl∑, sto∑, rcl∑, tot, mean, sdev, var, max∑,
 min∑, col∑, corr, cov, lr, predev, utpc, utpf, utpn, utpt, comb, perm

PRINT
 pr1, prst, prvar, prlcd, cr, trac, prstc, prusr, prmd

CONTRL
 sst, halt, abort, kill, wait, key, bepp,  cllcd,  disp,  clmf, errn,
 errm

BRANCH
 if(*), iferr, then(*), else(*), end(*), start(*), for(*), next(*),
 step(*), ift, ifte, do, until, end, while, repeat, end
 
TEST
 !=(*), >(*), >=(*), <(*), <=(*), sf, cf, fs?, fc?, fs?c, fc?c, and, or,
 xor, not, same, ==(*), stof, rclf, type
 
CATALOG
 next, prev, scan, use, fetch, quit
 
UNITS
 convert

CURSOR (called MODE in program)
 ins, del, ← → ↑ ↓, std(*), fix(*), sci(*), eng, deg, rad, cmd, undo, last, ml,
 rdx, prmd

TRIG
 pi(*)(+), sin(*), asin(*), cos(*), acos(*), tan(*), atan(*), p→r, r→p,
 r→c, c→r, arg, →hms, hms→, hms+, hms-, (*)d→r, (*)r→d

LOGS
 log(*), alog(*), ln(*), exp(*), lnp1, expm, sinh(*), asinh(*), cosh(*),
 acosh(*), tanh(*), atanh(*)

SOLV
 steq, rceq, isol, quad, show, root,

PLOT
 ppar, steq, rceq, pmin, pmax, indep, draw, res, axes, centr, *w, *h,
 sto∑, rcl∑, col∑, scl∑, drw∑, cllcd, digtiz

CUSTOM
 menu, custom

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Other standard files:
  README
  TODO

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Other notes:

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