PP_FEVAL(PR_OPTIONS,PR_PATH,PR_COMMAND,varargin)

function RT_PP_SPEC = PP_FEVAL(PR_OPTIONS,PR_PATH,PR_COMMAND,varargin)
%RT_PP_SPEC = PP_FEVAL(PR_OPTIONS,PR_PATH,PR_COMMAND,varargin)
%
%   This function places a request in PR_PATH for a
%   PP server process to evaluate PR_COMMAND with parameters
%   given by the varargin. A PP specification is returned
%   which can be used to check the status of the request via
%   PP_CHECK and to retrieve the results via PP_RETRIEVE.
%   PP server processes must be manually started via the
%   command PP_SERVER. Behavior of this function can be
%   customized via the parameter PR_OPTIONS which is a text
%   string of the form "opt1=val1&opt2=val2;...." The options
%   allowed are:
%
%   PAUSE - When equal to a positive value,
%      the function will return only after processing of
%      the request has begun by one of the servers and this
%      routine will check every PR_PAUSE seconds. Otherwise,
%      this routine will return immediately.
%   PREFIX - A text string to be used as a prefix for all
%      communication files between this process and the server
%      processes. The default is 'PP_REQ'.

% This file and the DistributePP software package were created and
% are maintained by Michael D. DeVore. The package originated in
% November, 1999. Permission is granted by the author for anyone
% to use or modify this software provided that:
% (1) any modified files are documented internally to clearly indicate
%     that they have been modified from the original release; and
% (2) it is recognized that neigher Michael D. DeVore nor Washington
%     University assumes any liability for the use or misuse of the software.

% Default option values...

LV_PAUSE = 0;
LV_PREFIX = 'PP_REQ';

% Extract options...

LV_OPTION_TAIL = PR_OPTIONS;
while length(LV_OPTION_TAIL) > 0
   [LV_OPT,LV_OPTION_TAIL] = strtok(LV_OPTION_TAIL,'=');
   LV_OPT = deblank(strrep(LV_OPT,'&',''));
   [LV_VAL,LV_OPTION_TAIL] = strtok(LV_OPTION_TAIL,'&');
   LV_VAL = strrep(LV_VAL,'=','');
   
   if strcmp('PAUSE',upper(LV_OPT)) == 1
      LV_PAUSE = str2double(LV_VAL);
   end

   if strcmp('PREFIX',upper(LV_OPT)) == 1
      LV_PREFIX = LV_VAL;
   end
end

% Generate a unique name for this request...

LV_SUFFIX = num2str(PP_SEQUENCE([PR_PATH LV_PREFIX '.seq']));
RT_PP_SPEC = [PR_PATH LV_PREFIX '_' LV_SUFFIX];

% Save all information necessary to satisfy the request...

LV_PROC_SPEC.Arguments = varargin;
LV_PROC_SPEC.Command = PR_COMMAND;
LV_PROC_SPEC.Options = PR_OPTIONS;
LV_PROC_SPEC.WorkingDir = pwd;

LV_PROC_SPEC.Path = '';
LV_LOC_PATH = path;
LV_DEF_PATH = pathdef;
while (length(LV_LOC_PATH)>1)
   [LV_TOK,LV_LOC_PATH] = strtok(LV_LOC_PATH,':');
   if (isempty(findstr(LV_DEF_PATH,LV_TOK)))
      LV_PROC_SPEC.Path = [LV_PROC_SPEC.Path LV_TOK ':'];
   end
end

save(RT_PP_SPEC,'LV_PROC_SPEC');

% Create the file indicating a request for service...

fclose(fopen([RT_PP_SPEC '.req'],'w'));

% If requested, wait until the file indicating the request has been picked up...

if LV_PAUSE > 0
   LV_FP = fopen([RT_PP_SPEC '.prc'],'r');;
   while LV_FP < 0
      pause(LV_PAUSE)
      LV_FP = fopen([RT_PP_SPEC '.prc'],'r');
   end
   fclose(LV_FP);
end