feat(tdis): error check for invalid time step lengths

Added a new error check for very small time steps.  If the value of startime plus the time step length is equal to endtime, then the time step is too small to be differentiated by the program based on the precision of floating point numbers.  The program will terminate with an error in this case.  The program will also terminate if the storage package and a transient stress period has a time step length of zero.   Closes #42.

README.md

@@ -7,7 +7,7 @@
 
 ## Automated Testing Status on Travis-CI
 
-### Version 6.0.3 develop — build 22
+### Version 6.0.3 develop — build 23
 [![Build Status](https://travis-ci.org/MODFLOW-USGS/modflow6.svg?branch=develop)](https://travis-ci.org/MODFLOW-USGS/modflow6)
 
 ## Introduction
@@ -31,7 +31,7 @@ MODFLOW 6 is the latest core version of MODFLOW. It synthesizes many of the capa
 
 #### ***Software/Code citation for MODFLOW 6:***
 
-[Langevin, C.D., Hughes, J.D., Banta, E.R., Provost, A.M., Niswonger, R.G., and Panday, Sorab, 2018, MODFLOW 6 Modular Hydrologic Model version 6.0.3 — develop: U.S. Geological Survey Software Release, 25 September 2018, https://doi.org/10.5066/F76Q1VQV](https://doi.org/10.5066/F76Q1VQV)
+[Langevin, C.D., Hughes, J.D., Banta, E.R., Provost, A.M., Niswonger, R.G., and Panday, Sorab, 2018, MODFLOW 6 Modular Hydrologic Model version 6.0.3 — develop: U.S. Geological Survey Software Release, 27 September 2018, https://doi.org/10.5066/F76Q1VQV](https://doi.org/10.5066/F76Q1VQV)
 
 
 ## Instructions for building definition files for new packages

code.json

@@ -1,26 +1,26 @@
 [
     {
         "status": "Release Candidate", 
-        "languages": [
-            "Fortran2008"
-        ], 
+        "downloadURL": "https://code.usgs.gov/usgs/modflow/modflow6/archive/master.zip", 
         "repositoryURL": "https://code.usgs.gov/usgs/modflow/modflow6.git", 
+        "laborHours": -1, 
         "disclaimerURL": "https://code.usgs.gov/usgs/modflow/modflow6/blob/master/DISCLAIMER.md", 
-        "name": "modflow6", 
         "tags": [
             "MODFLOW", 
             "groundwater model"
         ], 
+        "description": "MODFLOW is the USGS's modular hydrologic model. MODFLOW is considered an international standard for simulating and predicting groundwater conditions and groundwater/surface-water interactions.", 
+        "languages": [
+            "Fortran2008"
+        ], 
         "contact": {
             "name": "Christian D. Langevin", 
             "email": "langevin@usgs.gov"
         }, 
-        "downloadURL": "https://code.usgs.gov/usgs/modflow/modflow6/archive/master.zip", 
         "vcs": "git", 
-        "laborHours": -1, 
-        "version": "6.0.3.22", 
+        "version": "6.0.3.23", 
         "date": {
-            "metadataLastUpdated": "2018-09-25"
+            "metadataLastUpdated": "2018-09-27"
         }, 
         "organization": "U.S. Geological Survey", 
         "permissions": {
@@ -33,6 +33,6 @@
             "usageType": "openSource"
         }, 
         "homepageURL": "https://code.usgs.gov/usgs/modflow/modflow6/", 
-        "description": "MODFLOW is the USGS's modular hydrologic model. MODFLOW is considered an international standard for simulating and predicting groundwater conditions and groundwater/surface-water interactions."
+        "name": "modflow6"
     }
 ]

doc/ReleaseNotes/ReleaseNotes.tex

@@ -122,7 +122,7 @@ \section{History}
 \begin{itemize}
 \item Addressed issue with pointing contiguous pointer vectors/arrays to non-contiguous pointer vectors/arrays that caused code compilation failure with gfortran-8. A consequence of addressing this issue is that all pointer vectors/arrays that are allocated or pointed to using the memory manager must be defined to be contiguous.
 \item Corrected a problem with the reading of grid data from a binary file, in which the program was reading a binary header for each row of data.
-\item - 
+\item Added a new error check for very small time steps.  If the value of startime plus the time step length is equal to endtime, then the time step is too small to be differentiated by the program based on the precision of floating point numbers.  The program will terminate with an error in this case.  The program will also terminate if the storage package and a transient stress period has a time step length of zero.
 \end{itemize}
 
 \underline{STRESS PACKAGES}

doc/version.tex

@@ -1,3 +1,3 @@
-\newcommand{\modflowversion}{mf6.0.3.22}
-\newcommand{\modflowdate}{September 25, 2018}
+\newcommand{\modflowversion}{mf6.0.3.23}
+\newcommand{\modflowdate}{September 27, 2018}
 \newcommand{\currentmodflowversion}{Version \modflowversion---\modflowdate}

src/Model/GroundWaterFlow/gwf3sto8.f90

@@ -241,6 +241,9 @@ subroutine sto_fc(this, kiter, nodes, hold, hnew, nja, njasln, amat, &
 !
 !    SPECIFICATIONS:
 ! ------------------------------------------------------------------------------
+    ! -- modules
+    use SimModule, only: ustop, store_error
+    use ConstantsModule, only: LINELENGTH
     use TdisModule, only: delt
     ! -- dummy
     class(GwfStoType) :: this
@@ -260,11 +263,23 @@ subroutine sto_fc(this, kiter, nodes, hold, hnew, nja, njasln, amat, &
     real(DP) :: snold, snnew
     real(DP) :: ss0, ss1, ssh0, ssh1
     real(DP) :: rhsterm
+    character(len=LINELENGTH) :: errmsg
+    ! -- formats
+    character(len=*), parameter :: fmtsperror =                                &
+      &"('DETECTED TIME STEP LENGTH OF ZERO.  GWF STORAGE PACKAGE CANNOT BE ', &
+      &'USED UNLESS DELT IS NON-ZERO.')"
 ! ------------------------------------------------------------------------------
     !
     ! -- test if steady-state stress period
     if (this%iss /= 0) return
     !
+    ! -- Ensure time step length is not zero
+    if (delt == DZERO) then
+      write(errmsg, fmtsperror)
+      call store_error(errmsg)
+      call ustop()
+    endif
+    !
     ! -- set variables
     tled = DONE / delt
     !

src/Timing/tdis.f90

@@ -535,10 +535,6 @@ subroutine tdis_read_timing()
        &'     MULTIPLIER FOR DELT',/1X,76('-'))"
     character(len=*), parameter :: fmtrow =                                    &
       "(1X,I8,1PG21.7,I7,0PF25.3)"
-    character(len=*), parameter :: fmtpwarn =                                  &
-      "(1X,/1X,                                                                &
-        &'WARNING: PERLEN MUST NOT BE 0.0 FOR TRANSIENT STRESS PERIODS')"
-    !data
 ! ------------------------------------------------------------------------------
     !
     ! -- get PERIODDATA block
@@ -554,26 +550,11 @@ subroutine tdis_read_timing()
         nstp(n) = parser%GetInteger()
         tsmult(n) = parser%GetDouble()
         write (iout, fmtrow) n, perlen(n), nstp(n), tsmult(n)
-        !
-        !-----stop if nstp le 0, perlen eq 0 for transient stress periods,
-        !-----tsmult le 0, or perlen lt 0..
-        if(nstp(n) <= 0) then
-           call store_error( &
-             'THERE MUST BE AT LEAST ONE TIME STEP IN EVERY STRESS PERIOD')
-        end if
-        if(perlen(n) == dzero) then
-           write(iout, fmtpwarn)
-        end if
-        if(tsmult(n) <= dzero) then
-           call store_error( &
-            'TSMULT MUST BE GREATER THAN 0.0')
-        end if
-        if(perlen(n).lt.dzero) then
-           call store_error( &
-            'PERLEN CANNOT BE LESS THAN 0.0 FOR ANY STRESS PERIOD')
-        end if
         totalsimtime = totalsimtime + perlen(n)
       enddo
+      !
+      ! -- Check timing information
+      call check_tdis_timing(nper, perlen, nstp, tsmult)
       call parser%terminateblock()
       !
       ! -- Check for errors
@@ -592,6 +573,100 @@ subroutine tdis_read_timing()
     ! -- Return
     return
   end subroutine tdis_read_timing
+
+  subroutine check_tdis_timing(nper, perlen, nstp, tsmult)
+! ******************************************************************************
+! check_tdis_timing -- Check the tdis timing information.  Return back to 
+!   tdis_read_timing if an error condition is found and let the ustop
+!   routine be called there instead so the StoreErrorUnit routine can be
+!   called to assign the correct file name.
+! ******************************************************************************
+!
+!    SPECIFICATIONS:
+! ------------------------------------------------------------------------------
+    ! -- modules
+    use ConstantsModule, only: LINELENGTH, DZERO, DONE
+    use SimModule, only: ustop, store_error, count_errors
+    ! -- dummy
+    integer(I4B), intent(in) :: nper
+    real(DP), dimension(:), contiguous, intent(in) :: perlen
+    integer(I4B), dimension(:), contiguous, intent(in) :: nstp
+    real(DP), dimension(:), contiguous, intent(in) :: tsmult
+    ! -- local
+    integer(I4B) :: kper, kstp
+    real(DP) :: tstart, tend, dt
+    character(len=LINELENGTH) :: errmsg
+    ! -- formats
+    character(len=*), parameter :: fmtpwarn =                                   &
+      &"(1X,/1X,'PERLEN IS ZERO FOR STRESS PERIOD ', I0,                        &
+      &'. PERLEN MUST NOT BE ZERO FOR TRANSIENT PERIODS.')"
+    character(len=*), parameter :: fmtsperror =                                 &
+      &"(A,' FOR STRESS PERIOD ', I0)"
+    character(len=*), parameter :: fmtdterror =                                 &
+      &"('TIME STEP LENGTH OF ', G0, ' IS TOO SMALL IN PERIOD ', I0,            &
+      &' AND TIME STEP ', I0)"
+! ------------------------------------------------------------------------------
+    !
+    ! -- Initialize
+    tstart = DZERO
+    !
+    ! -- Go through and check each stress period
+    do kper = 1, nper
+      !
+      ! -- Error if nstp less than or equal to zero
+      if(nstp(kper) <= 0) then
+        write(errmsg, fmtsperror) 'NUMBER OF TIME STEPS LESS THAN ONE ', kper
+        call store_error(errmsg)
+        return
+      end if
+      !
+      ! -- Warn if perlen is zero
+      if(perlen(kper) == DZERO) then
+         write(iout, fmtpwarn) kper
+         return
+      end if
+      !
+      ! -- Error if tsmult is less than zero
+      if(tsmult(kper) <= DZERO) then
+        write(errmsg, fmtsperror) 'TSMULT MUST BE GREATER THAN 0.0 ', kper
+        call store_error(errmsg)
+        return
+      end if
+      !
+      ! -- Error if negative period length
+      if(perlen(kper) < DZERO) then
+        write(errmsg, fmtsperror) 'PERLEN CANNOT BE LESS THAN 0.0 ', kper
+        call store_error(errmsg)
+        return
+      end if
+      !
+      ! -- Go through all time step lengths and make sure they are valid
+      do kstp = 1, nstp(kper)
+        if (kstp == 1) then
+          dt = perlen(kper) / float(nstp(kper))
+          if(tsmult(kper) /= DONE)                                              &
+              dt = perlen(kper) * (DONE-tsmult(kper)) /                         &
+                  (DONE - tsmult(kper) ** nstp(kper))
+        else
+          dt = dt * tsmult(kper)
+        endif
+        tend = tstart + dt
+        !
+        ! -- Error condition if tstart == tend
+        if (tstart == tend) then
+          write(errmsg, fmtdterror) dt, kper, kstp
+          call store_error(errmsg)
+          return
+        endif
+      enddo
+      !
+      ! -- reset tstart = tend
+      tstart = tend
+      !
+    enddo
+    ! -- Return
+    return
+  end subroutine check_tdis_timing
 
   subroutine subtiming_begin(isubtime, nsubtimes, idsolution)
 ! ******************************************************************************

src/Utilities/version.f90

@@ -3,7 +3,7 @@ module VersionModule
   public
   ! -- modflow 6 version
   integer(I4B), parameter :: IDEVELOPMODE = 1
-  character(len=40), parameter :: VERSION = '6.0.3.22 09/25/2018'
+  character(len=40), parameter :: VERSION = '6.0.3.23 09/27/2018'
   character(len=10), parameter :: MFVNAM = ' 6'
   character(len=*), parameter  :: MFTITLE =                                     &
     'U.S. GEOLOGICAL SURVEY MODULAR HYDROLOGIC MODEL'

version.txt

@@ -1,12 +1,12 @@
 # MODFLOW 6 version file automatically created using...pre-commit.py
-# created on...September 25, 2018 17:06:18
+# created on...September 27, 2018 16:51:25
 
 # add some comments on how this version file
 # should be manually updated and used
 
 major = 6
 minor = 0
 micro = 3
-build = 22
-commit = 123
+build = 23
+commit = 124