diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..9bd9b01
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+*.~undo-tree~
diff --git a/LICENSE b/LICENSE
new file mode 100644
index 0000000..f288702
--- /dev/null
+++ b/LICENSE
@@ -0,0 +1,674 @@
+                    GNU GENERAL PUBLIC LICENSE
+                       Version 3, 29 June 2007
+
+ Copyright (C) 2007 Free Software Foundation, Inc. <https://fsf.org/>
+ Everyone is permitted to copy and distribute verbatim copies
+ of this license document, but changing it is not allowed.
+
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+ALL NECESSARY SERVICING, REPAIR OR CORRECTION.
+
+  16. Limitation of Liability.
+
+  IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
+WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MODIFIES AND/OR CONVEYS
+THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY
+GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE
+USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF
+DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD
+PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS),
+EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF
+SUCH DAMAGES.
+
+  17. Interpretation of Sections 15 and 16.
+
+  If the disclaimer of warranty and limitation of liability provided
+above cannot be given local legal effect according to their terms,
+reviewing courts shall apply local law that most closely approximates
+an absolute waiver of all civil liability in connection with the
+Program, unless a warranty or assumption of liability accompanies a
+copy of the Program in return for a fee.
+
+                     END OF TERMS AND CONDITIONS
+
+            How to Apply These Terms to Your New Programs
+
+  If you develop a new program, and you want it to be of the greatest
+possible use to the public, the best way to achieve this is to make it
+free software which everyone can redistribute and change under these terms.
+
+  To do so, attach the following notices to the program.  It is safest
+to attach them to the start of each source file to most effectively
+state the exclusion of warranty; and each file should have at least
+the "copyright" line and a pointer to where the full notice is found.
+
+    <one line to give the program's name and a brief idea of what it does.>
+    Copyright (C) <year>  <name of author>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+Also add information on how to contact you by electronic and paper mail.
+
+  If the program does terminal interaction, make it output a short
+notice like this when it starts in an interactive mode:
+
+    <program>  Copyright (C) <year>  <name of author>
+    This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
+    This is free software, and you are welcome to redistribute it
+    under certain conditions; type `show c' for details.
+
+The hypothetical commands `show w' and `show c' should show the appropriate
+parts of the General Public License.  Of course, your program's commands
+might be different; for a GUI interface, you would use an "about box".
+
+  You should also get your employer (if you work as a programmer) or school,
+if any, to sign a "copyright disclaimer" for the program, if necessary.
+For more information on this, and how to apply and follow the GNU GPL, see
+<https://www.gnu.org/licenses/>.
+
+  The GNU General Public License does not permit incorporating your program
+into proprietary programs.  If your program is a subroutine library, you
+may consider it more useful to permit linking proprietary applications with
+the library.  If this is what you want to do, use the GNU Lesser General
+Public License instead of this License.  But first, please read
+<https://www.gnu.org/licenses/why-not-lgpl.html>.
diff --git a/app/main.f90 b/app/main.f90
new file mode 100644
index 0000000..8c50727
--- /dev/null
+++ b/app/main.f90
@@ -0,0 +1,224 @@
+program main
+    
+    use kind_parameter
+    use cust_fns
+    use data_types
+    use inputs
+    use elastance
+    use funcs
+    use ieee_arithmetic
+    implicit none
+
+    ! Declares initial variables
+    integer :: nstep, ncycle, rk, i, icycle, k, io, nan_count, inf_count, offset
+    real(dp) :: T, pini_sys, pini_pulm, h, t_val
+    type (arterial_network) :: a_cof
+    type (chambers) :: h_cof
+    type (valve) :: AV, MV, PV, TV
+    type (valve_system) :: v_cof
+    real(dp), allocatable, dimension(:) :: ELV, ELA, ERV, ERA
+    type (heart_elastance) :: elast, elast_half
+    real(dp) :: current_sol(22)
+    real(dp), allocatable :: sol(:, :)
+    real(dp), allocatable :: h_pres(:, :) 
+    real(dp), allocatable :: t_axis(:)
+    real(dp), dimension(22) :: k1, k2, k3, k4
+    character(len=50), dimension(22) :: headers
+    real(dp) :: scale_Rsys, scale_Csys, scale_Rpulm, scale_Cpulm
+    real(dp) :: scale_Emax, scale_EmaxLV, scale_EmaxRV
+    real(dp) :: rho
+    type (arterial_system) :: sys
+    type (arterial_system) :: pulm
+    type (chamber) :: LV, LA, RV, RA
+
+    ! Declares the namelists
+    namelist /INPUTS/ nstep, T, ncycle, pini_sys, pini_pulm, rk
+    namelist /VALVES/ AV, MV, PV, TV
+    namelist /ARTERIES/ scale_Rsys, scale_Csys, scale_Rpulm, scale_Cpulm, rho, sys, pulm
+    namelist /HEART/ scale_EmaxLV, scale_EmaxRV, scale_Emax, LV, LA, RV, RA
+
+    !!! Initialisation !!!
+    ! Defines initial variables
+    io = 42
+    open(action='read', file='inputs.nml', newunit=io)
+    read(nml=INPUTS, unit=io)
+    read(nml=VALVES, unit=io)
+    read(nml=ARTERIES, unit=io)
+    read(nml=HEART, unit=io)
+    close(io)
+
+    headers = [ character(len=50) :: 'Aortic Valve Flow', &
+        'Sinus Flow','Aortic Flow', &
+        'Tricuspid Valve Flow', &
+        'Pulmonary Valve Flow', &
+        'Arterial Flow', &
+        'Aterioles Flow', &
+        'Mitral Valve Flow', &
+        'Systemic Sinus Pressure', &
+        'Systemic Artery Pressure', &
+        'Systemic Venous Pressure', &
+        'Pulmonary Sinus Pressure', &
+        'Pulmonary Artery Pressure', &
+        'Pulmonary Venous Pressure', &
+        'Left Ventricular Volume', &
+        'Left Atrial Volume', &
+        'Right Ventricular Volume', &
+        'Right Atrial Volume', &
+        'Aortic Valve Status', &
+        'Mitral Valve Status',&
+        'Pulmonary Valve Status', &
+        'Tricuspid Valve Status']
+
+    ! Relevant arterial coefficients
+    call artery_input(sys, pulm, scale_Rsys, scale_Csys, scale_Rpulm, scale_Cpulm)
+    a_cof = arterial_network(sys, pulm, rho)
+
+    ! Relevant heart coefficients
+    call heart_input(LV, LA, RV, RA, T, scale_EmaxLV, scale_EmaxRV, scale_Emax)
+    h_cof = chambers(LV, LA, RV, RA)
+
+    ! Relevant valve coefficients
+    v_cof = valve_system(AV, MV, PV, TV)
+
+    !!! Main code !!!
+    ! Calculates elastance curves for the different chambers of the heart
+    allocate(t_axis(nstep))
+    h = T / real(nstep, dp)
+    t_val = 0.0_dp
+    do i = 1, nstep
+        t_axis(i) = t_val
+        t_val = t_val + h
+    end do
+    allocate(ELV(nstep))
+    allocate(ELA(nstep))
+    allocate(ERV(nstep))
+    allocate(ERA(nstep))
+    ELV = calc_elastance(h_cof%LV, nstep, T, t_axis)
+    ELA = calc_elastance(h_cof%LA, nstep, T, t_axis)
+    ERV = calc_elastance(h_cof%RV, nstep, T, t_axis)
+    ERA = calc_elastance(h_cof%RA, nstep, T, t_axis)
+
+    ! Saves the heart information at the points
+    elast = heart_elastance(ELV=ELV, ELA=ELA, ERV=ERV, ERA=ERA)
+    elast_half = heart_elastance(ELV=midpoint(ELV), &
+        ELA=midpoint(ELA), &
+        ERV=midpoint(ERV), &
+        ERA=midpoint(ERA))
+
+    ! Initialise the solution
+    allocate(sol(22, ncycle * nstep + 1))
+
+    sol(1, 1) = 0.0_dp   ! Flow through aortic valve
+    sol(2, 1) = 0.0_dp   ! Flow through sinus
+    sol(3, 1) = 0.0_dp   ! Flow through aorta
+    sol(4, 1) = 0.0_dp   ! Flow through tricuspid
+    sol(5, 1) = 0.0_dp   ! Flow through pulmonary
+    sol(6, 1) = 0.0_dp   ! Flow through arteries
+    sol(7, 1) = 0.0_dp   ! Flow through arterioles
+    sol(8, 1) = 0.0_dp   ! Flow through mitral valve
+
+    sol(9, 1) = pini_sys    ! Initial arterial pressure
+    sol(10, 1) = pini_sys    ! Initial arterial pressure
+    sol(11, 1) = pini_sys    ! Initial arterial pressure
+    sol(12, 1) = pini_pulm    ! Initial pulmonary pressure
+    sol(13, 1) = pini_pulm    ! Initial pulmonary pressure
+    sol(14, 1) = pini_pulm    ! Initial pulmonary pressure
+
+    sol(15, 1) = h_cof%LV%v0_2    ! End diastolic left ventricular volume
+    sol(16, 1) = h_cof%LA%v0_2    ! End diastolic left atrial volume
+    sol(17, 1) = h_cof%RV%v0_2    ! End diastolic right ventricular volume
+    sol(18, 1) = h_cof%RA%v0_2    ! End diastolic right atrial volume
+
+    sol(19, 1) = 0.0_dp  ! Aortic valve is initially closed.
+    sol(20, 1) = 0.0_dp  ! Mitral valve is initially closed.
+    sol(21, 1) = 0.0_dp  ! Pulmonary valve is initially closed.
+    sol(22, 1) = 0.0_dp  ! Tricuspid valve is initially closed.
+
+    ! Solves the system of equations using a 4th order Runge-Kutta method
+    i = 0 ! Initialise
+
+    do icycle = 1, ncycle
+        print *, 'Cycle: ', icycle
+        do k = 1, nstep
+            i = i + 1
+            current_sol = sol(:, i)
+            if (rk == 2) then ! Second order Runge-Kutta
+                k1 = h * solver(current_sol, a_cof, v_cof, h_cof, elast, k)
+                k2 = h * solver(current_sol + k1/2, a_cof, v_cof, h_cof, elast, k)
+                sol(:, i+1) = current_sol + k2
+            else if (rk == 4) then ! Fourth order Runge-Kutta
+                k1 = h * solver(current_sol, a_cof, v_cof, h_cof, elast, k)
+                k2 = h * solver(current_sol + k1/2, a_cof, v_cof, h_cof, elast, k)
+                k3 = h * solver(current_sol + k2/2, a_cof, v_cof, h_cof, elast, k)
+                if ( k /= nstep ) then
+                    k4 = h * solver(current_sol + k3, a_cof, v_cof, h_cof, elast, k+1)
+                else
+                    k4 = h * solver(current_sol + k3, a_cof, v_cof, h_cof, elast, 1)
+                end if
+                sol(:, i + 1) = current_sol + (k1 + 2 * k2 + 2 * k3 + k4) / 6
+            end if
+        end do
+    end do
+
+    ! Calculates ventricular pressures
+    allocate(h_pres(4, nstep))
+    offset = (ncycle - 1) * nstep + 2
+    h_pres(1, :) = ELV * (sol(15, offset:) - LV%v0_1)
+    h_pres(2, :) = ELA * (sol(16, offset:) - LA%v0_1)
+    h_pres(3, :) = ERV * (sol(17, offset:) - RV%v0_1)
+    h_pres(4, :) = ERA * (sol(18, offset:) - RA%v0_1)
+
+    ! Saves the solution
+    io = 42
+    nan_count = 0
+    inf_count = 0
+    open(newunit=io, file='output.csv', status='replace')
+    do i=offset, ncycle * nstep
+        do k=1, 22
+            if ( i == offset ) then
+                write(io, fmt="(A, A)", advance='no') trim(headers(k)), ','
+                if ( k == 22 ) then
+                    write(io, fmt="(A)", advance='no') 'Left Ventricular Pressure,'
+                    write(io, fmt="(A)", advance='no') 'Left Atrial Pressure,'
+                    write(io, fmt="(A)", advance='no') 'Right Ventricular Pressure,'
+                    write(io, fmt="(A)", advance='no') 'Right Atrial Pressure,'
+                    write(io, fmt="(A)", advance='no') 'Left Ventricular Elastance,'
+                    write(io, fmt="(A)", advance='no') 'Left Atrial Elastance,'
+                    write(io, fmt="(A)", advance='no') 'Right Ventricular Elastance,'
+                    write(io, fmt="(A)", advance='no') 'Right Atrial Elastance,'
+                    write(io, fmt="(A)", advance='no') 'Time (s)'
+                end if
+            else
+                write(io, fmt="(f15.8, A)", advance='no') sol(k, i), ','
+                if ( k == 22 ) then
+                    write(io, fmt="(f15.8, A)", advance='no') h_pres(1, i - offset), ','
+                    write(io, fmt="(f15.8, A)", advance='no') h_pres(2, i - offset), ','
+                    write(io, fmt="(f15.8, A)", advance='no') h_pres(3, i - offset), ','
+                    write(io, fmt="(f15.8, A)", advance='no') h_pres(4, i - offset), ','
+                    write(io, fmt="(f15.8, A)", advance='no') ELV(i - offset), ','
+                    write(io, fmt="(f15.8, A)", advance='no') ELA(i - offset), ','
+                    write(io, fmt="(f15.8, A)", advance='no') ERV(i - offset), ','
+                    write(io, fmt="(f15.8, A)", advance='no') ERA(i - offset), ','
+                    write(io, fmt="(f15.8)", advance='no') t_axis(i - offset)
+                end if
+
+                if (ieee_is_nan(sol(k, i))) then
+                    nan_count = nan_count + 1
+                else if (.not. ieee_is_finite(sol(k, i))) then
+                    inf_count = inf_count + 1
+                end if
+            end if
+        end do
+        write(io, *)  ! New line
+    end do
+    close(io)
+
+    if (nan_count > 0) then
+        print *, 'NaN values found in solution.'
+        print *, '% NaN values:', 100.0_dp * nan_count / size(sol)
+        print *, '% Inf values:', 100.0_dp * inf_count / size(sol)
+    else
+        print *, 'Converged!'
+        print *, 'Mean value:', sum(sol) / size(sol)
+    end if
+end program main
diff --git a/fpm.toml b/fpm.toml
new file mode 100644
index 0000000..4289cf1
--- /dev/null
+++ b/fpm.toml
@@ -0,0 +1,14 @@
+name = "full_tree_lumped"
+version = "0.1.0"
+license = "license"
+author = "Alex Drysdale"
+maintainer = "reissuecardboard@duck.com"
+copyright = "Copyright 2022, Alex Drysdale"
+[build]
+auto-executables = true
+auto-tests = false
+auto-examples = true
+[install]
+library = false
+[dependencies]
+toml-f.git = "https://github.com/toml-f/toml-f"
diff --git a/src/cust_fns.f90 b/src/cust_fns.f90
new file mode 100644
index 0000000..0d9602a
--- /dev/null
+++ b/src/cust_fns.f90
@@ -0,0 +1,24 @@
+module cust_fns
+
+    use kind_parameter
+    implicit none
+
+    private
+    public midpoint
+
+contains
+
+    pure function midpoint(x) result(mp)
+
+        ! Declares initial variables
+        real(dp), allocatable, intent(in) :: x(:)
+        integer :: i
+        real(dp) :: dx(size(x) - 1)
+        real(dp) :: mp(size(x) - 1)
+
+        do i = 1, size(dx)
+            dx(i) = x(i + 1) - x(i)
+        end do
+        mp = x(1:size(x)-1) + dx / 2
+    end function midpoint
+end module cust_fns
diff --git a/src/data_types.f90 b/src/data_types.f90
new file mode 100644
index 0000000..58232fc
--- /dev/null
+++ b/src/data_types.f90
@@ -0,0 +1,80 @@
+module data_types
+
+    use kind_parameter
+    implicit none
+
+    private
+    public chamber, chambers
+    public arterial_system, arterial_network
+    public valve, valve_system
+    public heart_elastance
+
+    ! Declares the type for each chamber
+    type :: chamber
+        real(dp) :: Ks
+        real(dp) :: Emin
+        real(dp) :: Emax
+        real(dp) :: V0_1
+        real(dp) :: V0_2
+        real(dp) :: m1
+        real(dp) :: m2
+        real(dp) :: tau1
+        real(dp) :: tau2
+        real(dp) :: onset
+    end type
+
+    ! Declares the type for all 4 heart chambers
+    type :: chambers
+        type (chamber) :: LV
+        type (chamber) :: LA
+        type (chamber) :: RV
+        type (chamber) :: RA
+    end type
+
+    ! Declare artery system
+    type :: arterial_system
+        real(dp) :: Ras
+        real(dp) :: Rat
+        real(dp) :: Rar
+        real(dp) :: Rcp
+        real(dp) :: Rvn
+        real(dp) :: Cas
+        real(dp) :: Cat
+        real(dp) :: Cvn
+        real(dp) :: Las
+        real(dp) :: Lat
+    end type
+
+    ! Declares the complete network
+    type :: arterial_network
+        type (arterial_system) :: sys
+        type (arterial_system) :: pulm
+        real(dp) :: rho
+    end type
+
+    ! Declares the valve type
+    type :: valve
+        real(dp) :: Leff ! cm
+        real(dp) :: Aeffmin
+        real(dp) :: Aeffmax
+        real(dp) :: Kvc
+        real(dp) :: Kvo
+    end type
+
+    ! Declares a system of valves
+    type :: valve_system
+        type (valve) :: AV ! Aortic
+        type (valve) :: MV ! Mitral
+        type (valve) :: PV ! Pulmonary
+        type (valve) :: TV ! Tricuspid
+    end type
+
+    ! Declares the heart elastance type
+    type :: heart_elastance
+        real(dp), allocatable :: ELV(:)
+        real(dp), allocatable :: ELA(:)
+        real(dp), allocatable :: ERV(:)
+        real(dp), allocatable :: ERA(:)
+    end type
+
+end module data_types
diff --git a/src/elastance.f90 b/src/elastance.f90
new file mode 100644
index 0000000..e4150d6
--- /dev/null
+++ b/src/elastance.f90
@@ -0,0 +1,89 @@
+module elastance
+
+    use kind_parameter
+    use data_types
+    implicit none
+
+    private
+    public calc_elastance
+
+contains
+
+    elemental function mult(a, b) result(c)
+        real(dp), intent(in) :: a
+        real(dp), intent(in) :: b
+        real(dp) :: c
+        c = a * b
+    end function
+
+    elemental function calc_g1(g1_1) result(g1_2)
+        real(dp), intent(in) :: g1_1
+        real(dp) :: g1_2
+        g1_2 = g1_1 / ( 1 + g1_1)
+    end function calc_g1
+
+    elemental function calc_g2(g2_1) result(g2_2)
+        real(dp), intent(in) :: g2_1
+        real(dp) :: g2_2
+        g2_2 = 1 / ( 1 + g2_1)
+    end function calc_g2
+
+    ! Calculates the elastance of the heart
+    pure function calc_elastance(LV, nstep, T, E_t) result(E_out)
+
+        ! Declares input variables
+        type(chamber), intent(in) :: LV
+        integer, intent(in) :: nstep
+        real(dp), intent(in) :: T
+        real(dp), intent(in) :: E_t(nstep)
+
+        ! Declares output variable
+        real(dp), dimension(nstep) :: E_out
+
+        ! Declares intermediate variables
+        real(dp), dimension(nstep) :: E_tmp
+        integer :: i, t_idx
+        real(dp), dimension(nstep) :: q
+        real(dp), dimension(nstep - 1) :: dt
+        real(dp), dimension(nstep) :: v
+        real(dp), dimension(nstep) :: g1_1 ! g1 in MATLAB
+        real(dp), dimension(nstep) :: g2_1
+        real(dp), dimension(nstep) :: g1_2 ! G1 in MATLAB
+        real(dp), dimension(nstep) :: g2_2
+        real(dp), dimension(nstep) :: g12_prod
+        real(dp) :: k
+        real(dp), dimension(nstep) :: p_tmp
+        real(dp), dimension(nstep) :: p
+        real(dp), parameter :: pi=4.D0*datan(1.D0)
+
+        ! Initialise output
+        E_out = 0
+
+        ! Defines variables
+        q = sin(2 * pi * E_t / ( 2 * T))
+        do i = 1, nstep - 1
+            dt(i) = E_t(i + 1) - E_t(i)
+        end do
+        v(1) = LV%V0_2
+        v(2:) = LV%V0_2 - q(2:) * dt
+
+        g1_1 = (E_t / (LV%tau1 * T)) ** LV%m1
+        g2_1 = (E_t / (LV%tau2 * T)) ** LV%m2
+        g1_2 = calc_g1(g1_1)
+        g2_2 = calc_g2(g2_1)
+        g12_prod = mult(g1_2, g2_2)
+        k = (LV%Emax - LV%Emin) / maxval(g12_prod)
+
+        E_tmp = (k * g12_prod) + LV%Emin
+        p_tmp = mult(E_tmp, (v - LV%V0_1))
+        p = mult(p_tmp, (1 - LV%Ks * q))
+
+        t_idx = count(E_t <= T - LV%onset)
+        if ( t_idx == nstep ) then
+            E_out = E_tmp
+        else
+            E_out(1:nstep-t_idx) = E_tmp(t_idx+1:)
+            E_out(1 + nstep-t_idx:) = E_tmp(:t_idx) 
+        end if
+    end function calc_elastance
+end module elastance
diff --git a/src/funcs.f90 b/src/funcs.f90
new file mode 100644
index 0000000..0816a3e
--- /dev/null
+++ b/src/funcs.f90
@@ -0,0 +1,170 @@
+module funcs
+
+    use kind_parameter
+    use data_types
+    implicit none
+
+    private
+    public solver
+
+contains
+
+    ! Solves the system
+    pure function solver(sol, a_cof, v_cof, h_cof, elast, k) result(ftot)
+
+        ! Declare input variables
+        real(dp), dimension(22), intent(in) :: sol
+        type (arterial_network), intent(in) :: a_cof
+        type (valve_system), intent(in) :: v_cof
+        type (chambers), intent(in) :: h_cof
+        type (heart_elastance), intent(in) :: elast
+        integer, intent(in) :: k
+
+        real(dp), dimension(22) :: ftot
+        real(dp) :: mmHg, resist, rho
+        real(dp) :: Qav, Qsas, Qsat, Qtv, Qpv, Qpas, Qpat, Qmv, Qpvn, Qsvn
+        real(dp) :: psas, psat, psvn, ppas, ppat, ppvn
+        real(dp) :: Vlv, Vla, Vrv, Vra
+        real(dp) :: ksi_av, ksi_mv, ksi_pv, ksi_tv
+        real(dp) :: plv, pla, prv, pra
+        real(dp), dimension(4) :: Aeff
+        real(dp), dimension(4) :: B
+        real(dp), dimension(4) :: Z
+        real(dp) :: dpav, dpmv, dppv, dptv
+
+        ! Initialises ftot to be zero
+        ftot = 0.0_dp
+
+        mmHg = 1333.0_dp
+        resist = 1.0_dp
+
+        ! Flows
+        Qav = sol(1)
+        Qsas = sol(2)
+        Qsat = sol(3)
+        Qtv = sol(4)
+        Qpv = sol(5)
+        Qpas = sol(6)
+        Qpat = sol(7)
+        Qmv = sol(8)
+
+        ! Pressures
+        psas = sol(9)
+        psat = sol(10)
+        psvn = sol(11)
+        ppas = sol(12)
+        ppat = sol(13)
+        ppvn = sol(14)
+
+        ! Volumes
+        Vlv = sol(15)
+        Vla = sol(16)
+        Vrv = sol(17)
+        Vra = sol(18)
+
+        ! Valves
+        ksi_av = sol(19)
+        ksi_mv = sol(20)
+        ksi_pv = sol(21)
+        ksi_tv = sol(22)
+
+        ! Blood density
+        rho = a_cof%rho
+
+        ! Pressures in the chambers of the heart
+        plv = elast%ELV(k) * (Vlv - h_cof%LV%V0_1)
+        pla = elast%ELA(k) * (Vla - h_cof%LA%V0_1)
+        prv = elast%ERV(k) * (VRv - h_cof%RV%V0_1)
+        pra = elast%ERA(k) * (VRa - h_cof%RA%V0_1)
+
+        ! Inductance and resistance systemic 
+        ftot(2) = (psas - psat - a_cof%sys%Ras * Qsas) / a_cof%sys%Las
+        ftot(3) = (psat - psvn - (a_cof%sys%Rat + a_cof%sys%Rar + a_cof%sys%Rcp)* Qsat) / a_cof%sys%Lat
+        Qsvn = (psvn  - pra) / a_cof%sys%Rvn
+
+        ! Inductance and resistance pulmonary
+        ftot(6) = (ppas - ppat - a_cof%pulm%Ras * Qpas) / a_cof%pulm%Las 
+        ftot(7) = (ppat - ppvn - (a_cof%pulm%Rat + a_cof%pulm%Rar + a_cof%pulm%Rcp)* Qpat) / a_cof%pulm%Lat
+        Qpvn = (ppvn - pla) / a_cof%pulm%Rvn
+
+        ! Compliance systemic
+        ftot(9) = (Qav - Qsas) / a_cof%sys%Cas
+        ftot(10) = (Qsas - Qsat) / a_cof%sys%Cat
+        ftot(11) = (Qsat - Qsvn) / a_cof%sys%Cvn
+
+        ! Compliance Pulmonary
+        ftot(12) = (Qpv - Qpas) / a_cof%pulm%Cas
+        ftot(13) = (Qpas - Qpat) / a_cof%pulm%Cat
+        ftot(14) = (Qpat - Qpvn) / a_cof%pulm%Cvn
+
+        ! Volume-Flow relations systemic
+        ftot(15) = Qmv- Qav
+        ftot(16) = Qpvn - Qmv
+        ftot(17) = Qtv - Qpv
+        ftot(18) = Qsvn - Qtv
+
+        !!! Aortic Valve !!!
+        ! Effective area of the valve
+        Aeff(1) = (v_cof%AV%Aeffmax - v_cof%AV%Aeffmin) * ksi_av + v_cof%AV%Aeffmin
+        ! Bernoulli resistance of the valve
+        B(1) = rho / (2 * Aeff(1) ** 2) * resist
+        ! Impedance of the valve
+        Z(1) = rho * v_cof%AV%Leff/Aeff(1)
+
+        ! Pressure-flow relations through valve
+        dpav = (plv - psas) * mmHg
+        ftot(1) = (dpav - B(1) * Qav * abs(Qav))/ Z(1)
+
+        if (dpav <= 0) then ! Valve closing
+            ftot(19) = ksi_av * v_cof%AV%Kvc * dpav 
+        else ! Valve opening
+            ftot(19) = (1 - ksi_av) * v_cof%AV%Kvo * dpav
+        end if
+
+        !!! Mitral Valve !!!
+        Aeff(2) = (v_cof%MV%Aeffmax - v_cof%MV%Aeffmin) * ksi_mv + v_cof%MV%Aeffmin
+        B(2) = rho / (2 * Aeff(2) ** 2) * resist
+        Z(2) = rho * v_cof%MV%Leff / Aeff(2)
+
+        ! Pressure-flow relations through valve
+        dpmv = (pla-plv)*mmHg
+        ftot(8) = (dpmv-B(2)*Qmv*abs(Qmv) )/Z(2)
+
+        if (dpmv <= 0)  then ! Valve closing
+            ftot(20) = ksi_mv*v_cof%MV%Kvc*dpmv
+        else  ! Valve opening
+            ftot(20) = (1-ksi_mv)*v_cof%MV%Kvo*dpmv
+        end if
+
+
+        !!! Pulmonary Valve !!!
+        Aeff(3) = (v_cof%PV%Aeffmax-v_cof%PV%Aeffmin)*ksi_pv + v_cof%PV%Aeffmin
+        B(3) = rho/(2 * Aeff(3) ** 2)*resist
+        Z(3) = rho*v_cof%PV%Leff/Aeff(3)
+
+        ! pressure-flow relations through valve
+        dppv = (prv-ppas)*mmHg
+        ftot(5) = (dppv-B(3)*Qpv*abs(Qpv) )/Z(3)   ! Qpv
+
+        if (dppv <= 0)  then !valve closing
+            ftot(21) = ksi_pv*v_cof%PV%Kvc*dppv
+        else ! valve opening
+            ftot(21) = (1-ksi_pv)*v_cof%PV%Kvo*dppv  ! ksi_pv
+        end if
+
+        !!! Tricuspic Valve !!!
+        Aeff(4) = (v_cof%TV%Aeffmax-v_cof%TV%Aeffmin)*ksi_tv + v_cof%TV%Aeffmin
+        B(4) = rho/(2*Aeff(4)**2)*resist
+        Z(4) = rho*v_cof%MV%Leff/Aeff(4)
+
+        ! pressure-flow relations through valve
+        dptv = (pra-prv)*mmHg
+        ftot(4) = (dptv-B(4)*Qtv*abs(Qtv) )/Z(4)   !Qtv
+
+        if (dptv <= 0)  then ! Valve closing
+            ftot(22) = ksi_tv*v_cof%TV%Kvc*dptv
+        else ! Valve opening
+            ftot(22) = (1-ksi_tv)*v_cof%TV%Kvo*dptv      !ksi_tv
+        end if
+    end function solver
+end module funcs
diff --git a/src/inputs.f90 b/src/inputs.f90
new file mode 100644
index 0000000..e2ff356
--- /dev/null
+++ b/src/inputs.f90
@@ -0,0 +1,78 @@
+module inputs
+    ! Heart Input Declaration
+    use kind_parameter
+    use data_types
+    implicit none
+
+    private
+    public heart_input, artery_input
+
+contains
+
+    ! Gets the heart input
+    subroutine heart_input(LV, LA, RV, RA, T, scale_EmaxLV, scale_EmaxRV, scale_Emax)
+
+        ! Defines initial variables
+        real(dp), intent(in) :: T
+        real(dp), intent(in) :: scale_EmaxLV
+        real(dp), intent(in) :: scale_EmaxRV
+        real(dp), intent(in) :: scale_Emax
+
+        type (chamber), intent(inout) :: LV
+        type (chamber), intent(inout) :: LA
+        type (chamber), intent(inout) :: RV
+        type (chamber), intent(inout) :: RA
+
+        ! Left Ventricle
+        LV%Emax = LV%Emax * scale_EmaxLV
+        LV%tau1 = LV%tau1 * T
+        LV%tau2 = LV%tau2 * T
+
+        ! Left Atrium
+        LA%Emax = LA%Emax * scale_Emax
+        LA%tau1 = LA%tau1 * T
+        LA%tau2 = LA%tau2 * T
+        LA%onset = LA%onset * T
+
+        ! Right Ventricle
+        RV%Emax = RV%Emax * scale_EmaxRV
+        RV%tau1 = RV%tau1 * T
+        RV%tau2 = RV%tau2 * T
+
+        ! Right Atrium
+        RA%Emax = RA%Emax * scale_Emax
+        RA%tau1 = RA%tau1 * T
+        RA%tau2 = RA%tau2 * T
+        RA%onset = RA%onset * T
+
+    end subroutine heart_input
+
+    ! Gets the artery input
+    subroutine artery_input(sys, pulm, scale_Rsys, scale_Csys, scale_Rpulm, scale_Cpulm)
+
+        ! Declare inputs
+        type (arterial_system), intent(inout) :: sys, pulm
+        real(dp), intent(in) :: scale_Rsys, scale_Csys, scale_Rpulm, scale_Cpulm
+
+        ! Systemic system
+        sys%Ras = sys%Ras * scale_Rsys
+        sys%Rat = sys%Rat * scale_Rsys
+        sys%Rar = sys%Rar * scale_Rsys
+        sys%Rcp = sys%Rcp * scale_Rsys
+
+        sys%Cas = sys%Cas * scale_Csys
+        sys%Cat = sys%Cat * scale_Csys
+        sys%Cvn = sys%Cvn * scale_Csys
+        
+        ! Pulmonary system
+        pulm%Ras = pulm%Ras * scale_Rpulm
+        pulm%Rat = pulm%Rat * scale_Rpulm
+        pulm%Rar = pulm%Rar * scale_Rpulm
+        pulm%Rcp = pulm%Rcp * scale_Rpulm
+
+        pulm%Cas = pulm%Cas * scale_Cpulm
+        pulm%Cat = pulm%Cat * scale_Cpulm
+        pulm%Cvn = pulm%Cvn * scale_Cpulm
+
+    end subroutine artery_input
+end module inputs
diff --git a/src/kind_parameter.f90 b/src/kind_parameter.f90
new file mode 100644
index 0000000..61b8039
--- /dev/null
+++ b/src/kind_parameter.f90
@@ -0,0 +1,22 @@
+!> Numerical storage size parameters for real and integer values
+module kind_parameter
+   implicit none
+   public
+
+   !> Single precision real numbers, 6 digits, range 10⁻³⁷ to 10³⁷-1; 32 bits
+   integer, parameter :: sp = selected_real_kind(6, 37)
+   !> Double precision real numbers, 15 digits, range 10⁻³⁰⁷ to 10³⁰⁷-1; 64 bits
+   integer, parameter :: dp = selected_real_kind(15, 307)
+   !> Quadruple precision real numbers, 33 digits, range 10⁻⁴⁹³¹ to 10⁴⁹³¹-1; 128 bits
+   integer, parameter :: qp = selected_real_kind(33, 4931)
+
+   !> Char length for integers, range -2⁷ to 2⁷-1; 8 bits
+   integer, parameter :: i1 = selected_int_kind(2)
+   !> Short length for integers, range -2¹⁵ to 2¹⁵-1; 16 bits
+   integer, parameter :: i2 = selected_int_kind(4)
+   !> Length of default integers, range -2³¹ to 2³¹-1; 32 bits
+   integer, parameter :: i4 = selected_int_kind(9)
+   !> Long length for integers, range -2⁶³ to 2⁶³-1; 64 bits
+   integer, parameter :: i8 = selected_int_kind(18)
+
+end module kind_parameter