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[DavidM]

(07-04-2017 08:41 PM)Gilles59 Wrote:  An exemple of DOPERM to solve cryptarithms

Code:


«
 { 0. 1. 2. 3. 4. 5. 6. 7. 8. 9. } 3.
 « 
  { 'S' 'H' 'E'}  STO
  IF '(SQ(10.*H+E)==1E2*S+10.*H+E) AND (S≠0) AND (H≠0)' THEN
   { 'S' 'H' 'E'} DUP «RCL» DOLIST = 1 'ENDPERM' STO 
  END
 »
 DOPERM 
»

Being able to put all the test conditions into an algebraic is a nice option for readability, but there's a price to pay: it really slows things down. Just as a test, I timed the above program compared to the following equivalent one, which simply uses standard RPL syntax for the checks instead of an algebraic:

Code:

\<<
 { 0. 1. 2. 3. 4. 5. 6. 7. 8. 9. } 3.
 \<<
  { 'S' 'H' 'E'}  STO
  IF

    @ '(SQ(10.*H+E)==1E2*S+10.*H+E) AND (S≠0) AND (H≠0)'

    H 10 * E + SQ
    S 100 * H 10 * + E +
    ==
    S 0 \=/ AND
    H 0 \=/ AND

  THEN
   { 'S' 'H' 'E'} DUP \<<RCL\>> DOLIST = 1 'ENDPERM' STO
  END
 \>>
 DOPERM
\>>

Both had the same results, but notice the timings:

algebraic tests: 241 seconds
RPL tests: 66 seconds

It might not matter much if you simply leave it to run unattended, but I thought it might be worth noting for folks who aren't aware of the difference.