I'm trying solve a system of coupled ordinary differential equations, formed by 7 ODEs in python, using solve_ivp or either implement a fuction for RK4.
The general physical problem is as follows:
Cooling of photovoltaic modules with heat exchanger coupling to the module. In this way, the module generates electrical energy and thermal energy.
I have a polynomial function, G(t) = 9.8385e-13*t^4 - 1.82918e-8*t^3 + 5.991355e-05*t^2 + 2.312059e-1*t + 25, which works for an approximate range of 0 < t < 9000, which represents solar radiation as a function of time of day.
This function was obtained through a "polyfit" applied to real data (file upload here. Its a CSV - https://files.fm/u/9y4evkf6c).
This function is used as input for the ODEs, which represent an electrical and a thermal system as a function of time.
To solve the electrical model, I created some scripts that solve the diode equation for the photovoltaic module in question, and the output of this script is the photovoltaic power (called in the PPV thermal model) generated as a function of the module temperature and radiation. This script works great and solves part of my problem.
My difficulty lies in solving the equations of the thermal model, which receives as input parameters G(t) and PPV.
The equations result in this system:
System of EDOS
Labels:
Tvidro = Tglass = T1
Tcel = Tpv = T2
Ttedlar = T3
Tabs = Tabsorber = T4
Ttubo = Ttube = T5
Tfsai = Tfluid_out = T6
Tiso = Tinsulation = T7
Using method/function for RK4, the complete code is like this (you can go direct to part "#DEFINE MODEL EQUATIONS - ODES)" :
import numpy as np
import matplotlib.pyplot as plt
import csv
from numpy.polynomial.polynomial import polyval
############################################################
with open('directory of data called teste_dados_radiacao',"r") as i:
rawdata = list(csv.reader(i, delimiter = ";"))
exampledata = np.array(rawdata[1:], dtype=float)
xdata = exampledata[:,0]
ydata = exampledata[:,1]
curve = np.array(np.polyfit(xdata, ydata, 4))
rev_curve = np.array(list(reversed(curve)), dtype=float)
print(rev_curve)
#G_ajustado = polyval(xdata, rev_curve)
""" plt.plot(xdata, ydata, label = "dados experimentais")
plt.plot(xdata, model, label = "model")
plt.legend()
plt.show() """
#############################################################
#CONSTANTS
Tamb = 25 #°C #ambient temperatura
SIGMA = 5.67e-8 #W/m2K4
E_VIDRO = 0.90 #between 0.85 e 0.83 #nasrin2017 0.04
VENTO = 2 #m/s
T_GROUND = Tamb + 2 #°C
T_CEU = 0.00552*Tamb**1.5
Vf = 1 #m/s
Do = 10e-3 #m
Di = 8e-3 #m
NS = 6*10 #number of cells
T_F_ENT = 20 #°C
#INPUTS
Tcel = 25
Tv = 25
Tiso = 30
Av = 1.638*0.982
ALPHA_VIDRO = 0.9
L_VIDRO = 3e-3 #m
RHO_VIDRO = 2500 #kg/m3
M_VIDRO = Av*L_VIDRO*RHO_VIDRO #kg
CP_VIDRO = 500 #j/kgK
K_VIDRO = 2 #W/mK
TAU_VIDRO = 0.95
Pac = 0.85
H_CELL = 0.156 #m
A_CELL = NS*H_CELL**2
ALPHA_CELL = 0.9
L_CEL = 3e-3
RHO_CEL = 2330
M_CEL = A_CELL*L_CEL*RHO_CEL #kg - estimated
CP_CEL = 900 #J/kgK
K_CEL = 140 #W/mK
BETA_T = 0.43/100 # %/°C
N_ELE_REF = 0.1368 #13.68%
N_ELE = N_ELE_REF*(1 - BETA_T*(Tcel - 25)) #273 + 25 - tcel kelvin
A_tedlar = Av
L_TEDLAR = 0.33e-3
RHO_TEDLAR = 1500
M_TEDLAR = Av*L_TEDLAR*RHO_TEDLAR
CP_TEDLAR = 1090 #1090 OU 2090
K_TEDLAR = 0.35
ALPHA_TEDLAR = 0.34 #doc nasa ou zero
#parameters
RHO_ABS = 2700
A_ABS = Av
CP_ABS =900
L_ABS = 3e-3 #mm
M_ABS = A_ABS*RHO_ABS*L_ABS
K_ABS = 300
A_ABS_TUBO = 10*1.60*0.01+0.154*9*0.01
A_ABS_ISO = Av-A_ABS_TUBO
RHO_TUBO = 2700
CP_TUBO = 900
N_TUBOS = 10
L_TUBO = N_TUBOS*1.6
M_TUBO = RHO_TUBO*L_TUBO*(3.1415/4)*(Do**2 - Di**2)
K_TUBO = 300
A_TUBO_F = 0.387 #pi*Di*(L*10 VOLTAS + R(156MM)*9)
A_TUBO_ISO = 0.484 #pi*Do*(L*10 VOLTAS + R(156MM)*9)
A_ISO = Av
RHO_ISO = 50
L_ISO = 40e-3
M_ISO = A_ISO*RHO_ISO*L_ISO
CP_ISO = 670
K_ISO = 0.0375
E_ISO = 0.75 #ESTIMATED
RHO_FLUIDO = 997
M_FLUIDO = L_TUBO*(3.1415/4)*Di**2*RHO_FLUIDO
CP_FLUIDO = 4186 #j/kgK
MI_FLUIDO = 0.890e-3 #Pa*s ou N/m2 * s
K_FLUIDO = 0.607
M_PONTO = 0.05 #kg/s ou 0.5 kg/m3
#DIMENSIONLESS
Pr = CP_FLUIDO*MI_FLUIDO/K_FLUIDO #water 25°C
Re = RHO_FLUIDO*Vf*Di/MI_FLUIDO
if (Re<=2300):
Nuf = 4.364
else:
Nuf = 0.023*(Re**0.8)*(Pr*0.4)*Re
#COEFFICIENTS
h_rad_vidro_ceu = SIGMA*E_VIDRO*(Tv**2 - T_CEU)*(Tv + T_CEU)
h_conv_vidro_amb = 2.8 + 3*VENTO
h_conv_tubo_fluido = 0.5*30#Nuf
h_cond_vidro_cel = 1/((L_VIDRO/K_VIDRO) + (L_CEL/K_CEL))
h_cond_cel_tedlar = 1/((L_TEDLAR/K_TEDLAR) + (L_CEL/K_CEL))
h_cond_tedlar_abs = 1/((L_TEDLAR/K_TEDLAR) + (L_ABS/K_ABS))
h_cond_abs_tubo = 1/((L_TUBO/K_TUBO) + (L_ABS/K_ABS))
h_cond_abs_iso = 1/((L_ISO/K_ISO) + (L_ABS/K_ABS))
h_cond_tubo_iso = 1/((L_ISO/K_ISO) + (L_TUBO/K_TUBO))
h_conv_iso_amb = h_conv_vidro_amb
h_rad_iso_ground = SIGMA*E_ISO*(Tiso**2 - T_GROUND**2)*(Tiso + T_GROUND)
#GROUPS
A1 = (1/(M_VIDRO*CP_VIDRO))*(ALPHA_VIDRO*Av)#*G(t)) G_ajustado = polyval(dt,rev_curve)
A2 = (1/(M_VIDRO*CP_VIDRO))*(Av*(h_rad_vidro_ceu + h_conv_vidro_amb + h_cond_vidro_cel))
A3 = (1/(M_VIDRO*CP_VIDRO))*Av*h_cond_vidro_cel
A4 = (1/(M_VIDRO*CP_VIDRO))*Av*(h_conv_vidro_amb + h_rad_vidro_ceu)
A5 = (1/(M_CEL*CP_CEL))*(Pac*A_CELL*TAU_VIDRO*ALPHA_CELL) #*G(t)
A6 = -1*A5*N_ELE #*G(t)
A7 = (1/(M_CEL*CP_CEL))*A_CELL*h_cond_vidro_cel
A8 = (1/(M_CEL*CP_CEL))*A_CELL*(h_cond_vidro_cel + h_cond_cel_tedlar)
A9 = (1/(M_CEL*CP_CEL))*A_CELL*h_cond_cel_tedlar
A10 = (1/(M_TEDLAR*CP_TEDLAR))*A_tedlar*(1 - Pac)*TAU_VIDRO*ALPHA_TEDLAR#G(t)
A11 = (1/(M_TEDLAR*CP_TEDLAR))*A_tedlar*(h_cond_cel_tedlar + h_cond_tedlar_abs)
A12 = (1/(M_TEDLAR*CP_TEDLAR))*A_tedlar*h_cond_cel_tedlar
A13 = (1/(M_TEDLAR*CP_TEDLAR))*A_tedlar*h_cond_tedlar_abs
A14 = (1/(M_ABS*CP_ABS))*A_ABS*h_cond_tedlar_abs
A15 = (1/(M_ABS*CP_ABS))*(A_ABS*h_cond_tedlar_abs + A_ABS_TUBO*h_cond_abs_tubo + A_ABS_ISO*h_cond_abs_iso)
A16 = (1/(M_ABS*CP_ABS))*A_ABS_TUBO*h_cond_abs_tubo
A17 = (1/(M_ABS*CP_ABS))*A_ABS_ISO*h_cond_abs_iso
A18 = (1/(M_TUBO*CP_TUBO))*A_ABS_TUBO*h_cond_abs_tubo
A19 = (1/(M_TUBO*CP_TUBO))*(A_ABS_TUBO*h_cond_abs_tubo + A_TUBO_F*h_conv_tubo_fluido + A_TUBO_ISO*h_cond_tubo_iso)
A20 = (1/(M_TUBO*CP_TUBO))*A_TUBO_F*h_conv_tubo_fluido*0.5
A21 = (1/(M_TUBO*CP_TUBO))*A_TUBO_ISO*h_cond_tubo_iso
A22 = (1/(M_FLUIDO*CP_FLUIDO))*A_TUBO_F*h_conv_tubo_fluido
A23 = (1/(M_FLUIDO*CP_FLUIDO))*(A_TUBO_F*h_conv_tubo_fluido*0.5 + M_PONTO*CP_FLUIDO)
A24 = (1/(M_FLUIDO*CP_FLUIDO))*(T_F_ENT*(M_PONTO*CP_FLUIDO - h_conv_tubo_fluido*A_TUBO_F*0.5))
A25 = (1/(M_ISO*CP_ISO))*A_ABS_ISO*h_cond_abs_iso
A26 = (1/(M_ISO*CP_ISO))*(A_ABS_ISO*h_cond_abs_iso + A_TUBO_ISO*h_cond_tubo_iso + A_ISO*h_conv_iso_amb + A_ISO*h_rad_iso_ground)
A27 = (1/(M_ISO*CP_ISO))*A_TUBO_ISO*h_cond_tubo_iso
A28 = (1/(M_ISO*CP_ISO))*A_ISO*(h_conv_iso_amb*Tamb + h_rad_iso_ground*T_GROUND)
#DEFINE MODEL EQUATIONS - ODES - (GLASS, PV CELL, TEDLAR, ABSORBER, TUBE, FLUID, INSULATION) # dT1dt = A1*G_ajustado - A2*x[0] + A3*x[1] + A4 # dT2dt = A5*G_ajustado - A6*G_ajustado + A7*x[0] - A8*x[1] + A9*x[2]# dT3dt = A10*G_ajustado - A11*x[2] + A12*x[1] +A13*x[3]
def SysEdo(x, k):#tv-x[0] tcel-x[1] ttedlar-x[2] tabs-x[3] ttubo-x[4] tiso-x[5] tfs-x[6]
dT1dt = A1*polyval(k,rev_curve) - A2*x[0] + A3*x[1] + A4
dT2dt = A5*polyval(k,rev_curve) - A6*polyval(k,rev_curve) + A7*x[0] - A8*x[1] + A9*x[2]
dT3dt = A10*polyval(k,rev_curve) - A11*x[2] + A12*x[1] +A13*x[3]
dT4dt = A14*x[2] - A15*x[3] + A16*x[4] + A17*x[5]
dT5dt = A18*x[3] - A19*x[4] + A20*x[6] + A20*T_F_ENT + A21*x[5]
dT6dt = A22*x[4] - A23*x[6] + A24
dT7dt = A25*x[3] - A26*x[5] + A27*x[4] + A28
Tdot = np.array([dT1dt, dT2dt, dT3dt, dT4dt, dT5dt, dT6dt, dT7dt])
return Tdot
#RungeKutta4
def RK4(f, x0, t0, tf, dt):
t = np.arange(t0, tf, dt) #time vector
nt = t.size #lenght of time vector
nx = x0.size #length of state variables?
x = np.zeros((nx,nt)) #initialize 2D vector
x[:,0] = x0 #initial conditions
#RK4 constants
for k in range(nt-1):
k1 = dt*f(t[k], x[:,k],k)
k2 = dt*f(t[k] + dt/2, x[:,k] + k1/2, k)
k3 = dt*f(t[k] + dt/2, x[:,k] + k2/2, k)
k4 = dt*f(t[k] + dt, x[:,k] + k3, k)
dx = (k1 + 2*k2 + 2*k2 + k4)/6
x[:,k+1] = x[:,k] + dx
return x,t
#Define problems
f = lambda t, x, k : SysEdo(x, k)
#initial state - t0 is initial time - tf is final time - dt is time step
x0 = np.array([30, 30, 30, 30, 30, 30, 30])
t0 = 0
tf = 1000
dt = 1
#EDO SOLVE
x, t = RK4(f, x0, t0, tf, dt)
plt.figure()
plt.plot(t, x[0], '-', label='Tvidro')
"""
plt.plot(t, x[1], '-', label='Tpv')
plt.plot(t, x[2], '-', label='Ttedlar')
plt.plot(t, x[3], '-', label='Tabs')
plt.plot(t, x[4], '-', label='Tiso')
plt.plot(t, x[5], '-', label='Ttubo')
plt.plot(t, x[6], '-', label='Tfsai')"""
plt.title('Gráfico')
plt.legend(['Tvidro', 'Tpv', 'Ttedlar', 'Tabs', 'Tiso', 'Ttubo', 'Tfsai'], shadow=False)
plt.xlabel('t (s)')
plt.ylabel('Temperatura (°C)')
plt.xlim(0,20)
plt.ylim(0,150)
plt.grid('on')
plt.show()
Thank you in advance, I am also open to completely start the implementation from scratch if there is a better way to do this with python or matlab.
You can just replace
x, t = RK4(f, x0, t0, tf, dt)
with
t = arange(t0,tf+0.5*dt,dt)
res = solve_ivp(f,(t0,tf),x0,t_eval=t,args=(k,), method="DOP853", atol=1e-6,rtol=1e-8)
x = res.y[0]
Adapt the last 3 parameters to your liking.
I'm trying to solve the 1-d wave equation, and I coding the program for numerical computing solutions and animating, saving data in the file. I don't know how to fix the error and finally get the working code.
u_tt = a**2 * u_xx + f(x,t)
It is necessary for the program to solve equations when entering both an additional function and with non-zero initial and boundary conditions, with graphic visualization and saving data to a file.
So I attach my code (Python 3.9), and error message:
import numpy as np
import math
import matplotlib.pyplot as plt
import os
import time
import glob
def sol(I, V, f, a, L, C, T, U_0, U_L, dt, user_func = None):
"""
solver for wave equation
u_tt = a**2*u_xx + f(x,t) (0,L) where u=0 for
x=0,L, for t in (0,T].
:param I:
:param V:
:param f:
:param a:
:param L:
:param C:
:param T:
:param U_0:
:param U_L:
:param dt:
:param user_func:
:return:
"""
nt = int(round(T / dt))
t = np.linspace(0, nt * dt, nt + 1) # array for time points
dx = dt * a / float(C)
nx = int(round(L / dx))
x = np.linspace(0, L, nx + 1) # array for coord points
q = a ** 2
C2 = (dt / dx) ** 2
dt2 = dt * dt
# --- checking f(x,t) ---
if f is None or f == 0:
f = lambda x, t: 0
# --- check the initial conds dU(x,0)/dt ---
if V is None or V == 0:
V = lambda x: 0
# boundary conds
if U_0 is not None:
if isinstance(U_0, (float, int)) and U_0 == 0:
U_0 = lambda t: 0
if U_L is not None:
if isinstance(U_L, (float, int)) and U_L == 0:
U_L = lambda t: 0
# --- allocate memory ---
u = np.zeros(nx + 1)
u_n = np.zeros(nx + 1)
u_nm = np.zeros(nx + 1)
# --- valid indexing check ---
Ix = range(0, nx + 1)
It = range(0, nt + 1)
# --- set the boundary conds ---
for i in range(0, nx + 1):
u_n[i] = I(x[i])
if user_func is not None:
user_func(u_n, x, t, 0)
# --- finite difference step ---
for i in Ix[1:-1]:
u[i] = u_n[i] + dt * V(x[i]) + 0.5 * C2 * (0.5 * (q[i] + q[i + 1]) * (u_n[i + 1] - u_n[i]) -
0.5 * (q[i] + q[i - 1]) * (u_n[i] - u_n[i - 1])) + 0.5 * dt2 * f(x[i], t[0])
i = Ix[0]
if U_0 is None:
# set the boundary conds (x=0: i-1 -> i+1 u[i-1]=u[i+1]
# where du/dn = 0, on x=L: i+1 -> i-1 u[i+1]=u[i-1])
ip1 = i + 1
im1 = ip1 # i-1 -> i+1
u[i] = u_n[i] + dt * V(x[i]) + \
0.5 * C2 * (0.5 * (q[i] + q[ip1]) * (u_n[ip1] - u_n[i]) - 0.5 * (q[i] + q[im1])
* (u_n[i] - u_n[im1])) + 0.5 * dt2 * f(x[i], t[0])
else:
u[i] = U_0(dt)
i = Ix[-1]
if U_L is None:
im1 = i - 1
ip1 = im1 # i+1 -> i-1
u[i] = u_n[i] + dt * V(x[i]) + \
0.5 * C2 * (0.5 * (q[i] + q[ip1]) * (u_n[ip1] - u_n[i]) - 0.5 * (q[i] + q[im1]) * (u_n[i] - u_n[im1])) + \
0.5 * dt2 * f(x[i], t[0])
else:
u[i] = U_L(dt)
if user_func is not None:
user_func(u, x, t, 1)
# update data
u_nm, u_n, u = u_n, u, u_nm
# --- time looping ---
for n in It[1:-1]:
# update all inner points
for i in Ix[1:-1]:
u[i] = - u_nm[i] + 2 * u_n[i] + \
C2 * (0.5 * (q[i] + q[i + 1]) * (u_n[i + 1] - u_n[i]) -
0.5 * (q[i] + q[i - 1]) * (u_n[i] - u_n[i - 1])) + dt2 * f(x[i], t[n])
# --- set boundary conds ---
i = Ix[0]
if U_0 is None:
# set the boundary conds
# x=0: i-1 -> i+1 u[i-1]=u[i+1] where du/dn=0
# x=L: i+1 -> i-1 u[i+1]=u[i-1] where du/dn=0
ip1 = i + 1
im1 = ip1
u[i] = - u_nm[i] + 2 * u_n[i] + \
C2 * (0.5 * (q[i] + q[ip1]) * (u_n[ip1] - u_n[i]) - 0.5 * (q[i] + q[im1]) * (u_n[i] - u_n[im1])) + \
dt2 * f(x[i], t[n])
else:
u[i] = U_0(t[n + 1])
i = Ix[-1]
if U_L is None:
im1 = i - 1
ip1 = im1
u[i] = - u_nm[i] + 2 * u_n[i] + \
C2 * (0.5 * (q[i] + q[ip1]) * (u_n[ip1] - u_n[i]) - 0.5 * (q[i] + q[im1]) * (u_n[i] - u_n[im1])) + \
dt2 * f(x[i], t[n])
else:
u[i] = U_L(t[n + 1])
if user_func is not None:
if user_func(u, x, t, n + 1):
break
u_nm, u_n, u = u_n, u, u_nm
return u, x, t
# --- here function for return functions ---
# return func(x)
def func(x):
"""
:param x:
:return:
"""
return # expression
# start simulate and animate or visualisation and savin the data from file
def simulate(
I, V, f, a, L, C, T, U_0, U_L, dt, # params
umin, umax, # amplitude
animate = True, # animate or not?
solver_func = sol, # call the solver
mode = 'plotter', # mode: plotting the graphic or saving to file
):
# code for visualization and simulate
...........
# start simulate
solver_func(I, V, f, a, L, C, T, U_0, U_L, dt, user_func)
return 0
def task( ):
'''
test tasking for solver and my problem
:return:
'''
I
L = 1
a = 1
C = 0.85
T = 1
dt = 0.05
U_0, U_L, V, f
umax = 2
umin = -umax
simulate(I, V, f, a, L, C, T, U_0, U_L, dt, umax, umin, animate = True, solver_func = sol, mode = 'plotter',)
if __name__ == '__main__':
task()
And I get the same error:
File "C:\\LR2-rep\wave_eq_1d.py", line 102, in sol
u[i] = u_n[i] + dt * V(x[i]) + 0.5 * C2 * (0.5 * (q[i] + q[i + 1]) * (u_n[i + 1] - u_n[i]) -
TypeError: 'int' object is not subscriptable
I understand the meaning of the error, but I do not understand how it can be fixed, and for almost two weeks I have not been able to write a program ... I ask for help with solving this problem! Thank you very much in advance!
I am converting an IDL code (written by Oleg Kochukhov) to Python. The code generates star surface map over spectral line profiles using Tikhonov or Maximum Entropy methods.
I use scipy.optimize.minimize to generate map over line profiles. But process is too slow and results is not compatible. I search solution on internet but i dont find any usefull solution.
I added a runnable code below:
import numpy as np
from scipy.optimize import minimize
import matplotlib.pyplot as plt
from mpl_toolkits.basemap import Basemap
import matplotlib.gridspec as gridspec
#syc = 0
def DI_GridInit(ntot):
# generate stellar surface grid
nlat = int(round(0.5 * (1.0 + np.sqrt(1.0 + np.pi * ntot))) - 1)
nlon = np.zeros(nlat, dtype=int)
xlat = np.pi * (np.arange(nlat, dtype=float) + 0.5) / nlat - np.pi / 2.0
xcirc = 2.0 * np.cos(xlat[1:])
nlon[1:] = np.around(xcirc * nlat) + 1
nlon[0] = ntot - sum(nlon[1:])
if abs(nlon[0] - nlon[nlat - 1]) > nlat:
nlon[1:] = nlon[1:] + (nlon[0] - nlon[nlat - 1]) / nlat
nlon[0] = ntot - sum(nlon[1:])
if nlon[0] < nlon[nlat - 1]:
nlon[1:] = nlon[1:] - 1
nlon[0] = ntot - sum(nlon[1:])
# generate Descartes coordinates for the surface grid in
# stellar coordinates, areas of surface elements and
# regularization indices: (lower, upper, right, left)
x0, j = np.zeros((ntot, 3), dtype=float), 0
latitude, longitude = np.zeros(ntot, dtype=float), np.zeros(ntot, dtype=float)
sa, ireg = np.zeros(ntot, dtype=float), np.zeros((ntot, 4), dtype=int)
slt = np.hstack((0., (xlat[1:nlat] + xlat[0:nlat - 1]) / 2. + np.pi / 2., np.pi))
for i in range(nlat):
coslat = np.cos(xlat[i])
sinlat = np.sin(xlat[i])
xlon = 2 * np.pi * (np.arange(nlon[i]) + 0.5) / nlon[i]
sinlon = np.sin(xlon)
coslon = np.cos(xlon)
x0[:, 0][j:j + nlon[i]] = coslat * sinlon
x0[:, 1][j:j + nlon[i]] = -coslat * coslon
x0[:, 2][j:j + nlon[i]] = sinlat
latitude[j:j + nlon[i]] = xlat[i]
longitude[j:j + nlon[i]] = xlon
sa[j:j + nlon[i]] = 2. * np.pi * (np.cos(slt[i]) - np.cos(slt[i + 1])) / nlon[i]
ireg[:, 2][j:j + nlon[i]] = np.roll(j + np.arange(nlon[i], dtype=int), -1)
ireg[:, 3][j:j + nlon[i]] = np.roll(j + np.arange(nlon[i], dtype=int), 1)
if (i > 0):
il_lo = j - nlon[i - 1] + np.arange(nlon[i - 1], dtype=int)
else:
il_lo = j + nlon[i] + np.arange(nlon[i + 1], dtype=int)
if (i < nlat - 1):
il_up = j + nlon[i] + np.arange(nlon[i + 1], dtype=int)
else:
il_up = il_lo
for k in range(j, j + nlon[i]):
dlat_lo = longitude[k] - longitude[il_lo]
ll = np.argmin(abs(dlat_lo))
ireg[k][0] = il_lo[ll]
dlat_up = longitude[k] - longitude[il_up]
ll = np.argmin(abs(dlat_up))
ireg[k][1] = il_up[ll]
j += nlon[i]
theta = np.arccos(x0[:, 2])
phi = np.arctan2(x0[:, 0], -x0[:, 1])
ii = np.argwhere(phi < 0).T[0]
nii = len(ii)
phi[ii] = 2.0 * np.pi - abs(phi[ii]) if nii else None
grid = {'ntot': ntot, 'nlat': nlat, 'nlon': nlon, 'xyz': x0, 'lat': latitude,
'lon': longitude, 'area': sa, 'ireg': ireg, 'phi': phi, 'theta': theta}
return grid
def DI_Map(grid, spots):
map = np.ones(grid['ntot'], dtype=float)
for i in range(spots['n']):
dlon = grid['lon'] - np.deg2rad(spots['tbl'][i, 0])
dlat = grid['lat'] - np.deg2rad(spots['tbl'][i, 1])
da = (2.0 * np.arcsin(np.sqrt(np.sin(0.5 * dlat) ** 2 +
np.cos(np.deg2rad(spots['tbl'][i, 1])) *
np.cos(grid['lat']) * np.sin(0.5 * dlon) ** 2)))
ii = np.argwhere(da <= np.deg2rad(spots['tbl'][i, 2])).T[0]
ni = len(ii)
map[ii] = spots['tbl'][i, 3] if ni > 0 else None
return map
def DI_Prf(grid, star, map, phase=None, vv=None, vr=None, nonoise=None):
# velocity array
if vv is not None:
nv = len(vv)
else:
nv = int(np.ceil(2.0 * star['vrange'] / star['vstep']))
vv = -star['vrange'] + np.arange(nv, dtype=float) * star['vstep']
# phase array
if phase is None:
phase = np.arange(star['nphases'], dtype=float) / star['nphases']
# velocity correction for each phase
vr = np.zeros(star['nphases'], dtype=float) if vr == None else None
# fixed trigonometric quantities
cosi = np.cos(np.deg2rad(star['incl'])); sini = np.sin(np.deg2rad(star['incl']))
coslat = np.cos(grid['lat']); sinlat = np.sin(grid['lat'])
# FWHM to Gaussian sigma
sigm = star['fwhm'] / np.sqrt(8.0 * np.log(2.0))
isig = (-0.5 / sigm ** 2)
# initialize line profile and integrated field arrays
prf = np.zeros((nv, len(phase)), dtype=float)
# gradient if called with 5 - variable input
grad = np.zeros((nv, len(phase), grid['ntot']), dtype=float)
# phase loop
for i in range(len(phase)):
coslon = np.cos(grid['lon'] + 2.0 * np.pi * phase[i])
sinlon = np.sin(grid['lon'] + 2.0 * np.pi * phase[i])
mu = sinlat * cosi + coslat * sini * coslon
ivis = np.argwhere(mu > 0.).T[0]
dv = -sinlon[ivis] * coslat[ivis] * star['vsini']
avis = grid['area'][ivis] * mu[ivis] * (1.0 - star['limbd'] + star['limbd'] * mu[ivis])
if star['type'] == 0:
wgt = avis * map[ivis]
wgtn = sum(wgt)
for j in range(nv):
plc = 1.0 - star['d'] * np.exp(isig * (vv[j] + dv - vr[i]) ** 2)
prf[j][i] = sum(wgt * plc) / wgtn
grad[j][i][ivis] = avis * plc / wgtn - avis * prf[j][i] / wgtn
elif star['type'] == 1:
wgt = avis
wgtn = sum(wgt)
for j in range(nv):
plc = 1.0 - map[ivis] * star['d'] * np.exp(isig * (vv[j] + dv - vr[i]) ** 2)
prf[j][i] = sum(wgt * plc) / wgtn
grad[j][i][ivis] = -wgt / wgtn * star['d'] * np.exp(isig * (vv[j] + dv - vr[i]) ** 2)
# output structure
syn = {'v': vv, 'phase': phase, 'prf': prf}
# add noise
if star['snr'] != -1 and nonoise != None:
obs = syn['prf'] * 0.0
for i in range(star['nphases']):
obs[:, i] = syn['prf'][:, i] + np.random.standard_normal((len(syn['v']),)) / star['snr']
syn['obs'] = obs
return syn, grad
def DI_func(cmap, functargs):
# global syc
star = functargs['star']
grid = functargs['grid']
obs = functargs['obs']
invp = functargs['invp']
nv = len(obs['v'])
er = 1.0 / abs(star['snr'])
if 'vr' in obs.keys():
syn, grad = DI_Prf(grid, star, cmap, phase=obs['phase'], vv=obs['v'], vr=obs['vr'])
else:
syn, grad = DI_Prf(grid, star, cmap, phase=obs['phase'], vv=obs['v'])
# shf = 0
# for i in range(len(obs['phase'])):
# plt.plot(obs['v'], obs['obs'][:, i] + shf, 'bo')
# plt.plot(obs['v'], syn['prf'][:, i] + shf, 'r')
# plt.plot(obs['v'], obs['obs'][:, i] - syn['prf'][:, i] + shf, 'k')
# shf += 0.1
# plt.show()
fchi = 0.0
sign = (-1) ** invp['regtype']
for i in range(star['nphases']):
fchi = fchi + sign * sum((syn['prf'][:, i] - obs['obs'][:, i]) ** 2 / er ** 2) / nv
freg = 0
if invp['lambda'] > 0:
if invp['regtype'] == 0:
ir = grid['ireg']
for k in range(len(ir[0, :])):
freg = freg + invp['lambda'] / grid['ntot'] * sum((cmap - cmap[ir[:, k]]) ** 2)
elif invp['regtype'] == 1:
mmap = sum(cmap) / grid['ntot']
nmap = cmap / mmap
freg = freg - invp['lambda'] / grid['ntot'] * sum(nmap * np.log(nmap))
ftot = fchi + freg
syn['obs'] = obs['obs']
# syc += 1
# if syc % 1000 == 0:
# plotting(grid, cmap, syn, star['incl'], typ=star['type'])
#
# print(syc, ftot, sum(cmap))
return ftot
def plotting(grid, map, syn, incl, typ):
nlon = grid['nlon']
nln = max(nlon)
nlt = len(nlon)
ll = np.zeros(nlt + 1, dtype=int)
ll[0] = 0
for i in range(nlt):
ll[i + 1] = ll[i] + nlon[i]
map1 = np.zeros((nlt, nln), dtype=float)
x = np.arange(nln, dtype=float) + 0.5
for i in range(nlt):
lll = ((np.arange(nlon[i] + 2, dtype=float) - 0.5) * nln) / nlon[i]
y = np.hstack((map[ll[i + 1] - 1], map[ll[i]:ll[i+1]-1], map[ll[i]]))
for j in range(nln):
imin = np.argmin(abs(x[j] - lll))
map1[i, j] = y[imin]
light = (190 * (map1 - np.min(map1)) / (np.max(map1) - np.min(map1))) + 50
light_rect = np.flipud(light)
if typ == 0:
cmap = 'gray'
else:
cmap = 'gray_r'
fig = plt.figure()
fig.clear()
spec = gridspec.GridSpec(ncols=3, nrows=3, left=0.10, right=0.98,
top=0.97, bottom=0.07, hspace=0.2, wspace=0.36)
# naive IDW-like interpolation on regular grid
shape = light.shape
nrows, ncols = (shape[0], shape[1])
lon, lat = np.meshgrid(np.linspace(0, 360, ncols), np.linspace(-90, 90, nrows))
for i, item in enumerate([[(0, 0), -0], [(0, 1), -90], [(1, 0,), -180], [(1, 1), -270]]):
ax = fig.add_subplot(spec[item[0]])
# set up map projection
m = Basemap(projection='ortho', lat_0=90 - incl, lon_0=item[1], ax=ax)
# draw lat/lon grid lines every 30 degrees.
m.drawmeridians(np.arange(0, 360, 30))
m.drawparallels(np.arange(-90, 90, 30))
# compute native map projection coordinates of lat/lon grid.
x, y = m(lon, lat)
# contour data over the map.
m.contourf(x, y, light, 15, vmin=0., vmax=255., cmap=cmap)
if i in [0, 2]:
x2, y2 = m(180 - item[1], incl)
else:
x2, y2 = m(180 + item[1], incl)
x1, y1 = (-10, 5)
ax.annotate(str('%0.2f' % (abs(item[1]) / 360.)), xy=(x2, y2), xycoords='data',
xytext=(x1, y1), textcoords='offset points',
color='r')
ax5 = fig.add_subplot(spec[-1, :2])
ax5.imshow(light_rect, vmin=0., vmax=255., cmap=cmap, interpolation='none', extent=[0, 360, -90, 90])
ax5.set_xticks(np.arange(0, 420, 60))
ax5.set_yticks(np.arange(-90, 120, 30))
ax5.set_xlabel('Longitude ($^\circ$)', fontsize=7)
ax5.set_ylabel('Latitude ($^\circ$)', fontsize=7)
ax5.tick_params(labelsize=7)
ax6 = fig.add_subplot(spec[0:, 2])
shf = 0.0
for i in range(len(syn['phase'])):
ax6.plot(syn['v'], syn['obs'][:, -i - 1] + shf, 'bo', ms=2)
ax6.plot(syn['v'], syn['prf'][:, -i - 1] + shf, 'r', linewidth=1)
ax6.text(min(syn['v']), max(syn['obs'][:, -i - 1] + shf), str('%0.2f' % syn['phase'][-i - 1]),
fontsize=7)
shf += 0.1
p1 = ax6.lines[0]
p2 = ax6.lines[-1]
p1datay = p1.get_ydata()
p1datax = p1.get_xdata()
p2datay = p2.get_ydata()
y1, y2 = min(p1datay) - min(p1datay) / 20.,max(p2datay) + min(p1datay) / 10.
ax6.set_ylim([y1, y2])
ax6.set_xlabel('V ($km s^{-1}$)', fontsize=7)
ax6.set_ylabel('I / Ic', fontsize=7)
ax6.tick_params(labelsize=7)
max_ = int(max(p1datax))
ax6.set_xticks([-max_, np.floor(-max_ / 2.), 0.0, np.ceil(max_ / 2.), max_])
plt.show()
if __name__ == "__main__":
# Star parameters
star = {'ntot': 1876, 'type': 0, 'incl': 70, 'vsini': 50, 'fwhm': 7.0, 'd': 0.6,
'limbd': 0.5, 'nphases': 5, 'vrange': np.sqrt(50 ** 2 + 7.0 ** 2) * 1.4,
'vstep': 1.0, 'snr': 500}
# Spot parameters
lon_spot = [40, 130, 220, 310]
lat_spot = [-30, 0, 60, 30]
r_spot = [20, 20, 20, 20]
c_spot = [0.1, 0.2, 0.25, 0.3]
tbl = np.array([lon_spot, lat_spot, r_spot, c_spot]).T
spots = {'n': len(lon_spot), 'type': star['type'], 'tbl': tbl}
# Generate grid
grid = DI_GridInit(star['ntot'])
# Generate map
cmap = DI_Map(grid, spots)
# Generate spectral line profiles
csyn, grad = DI_Prf(grid, star, cmap, nonoise=True)
# Plotting map and line profiles
plotting(grid, cmap, csyn, star['incl'], star['type'])
# Generate map over the line profiles using scipy.optimize.minimize
invp = {'lambda': 20, 'regtype': 0, 'maxiter': 10}
grid_inv = DI_GridInit(star['ntot'])
functargs = {'star': star, 'grid': grid_inv, 'obs': csyn, 'invp': invp}
cmap = np.ones(star['ntot'])
cmap[0] = 0.99
bnd = list(zip(np.zeros(len(cmap), dtype=float), np.ones(len(cmap), dtype=float)))
minimize(DI_func, cmap, args=functargs, method='TNC', bounds=bnd,
callback=None, options={'eps': 0.1, 'maxiter': 5, 'disp': True})
The code includes followed parts.
'DI_GridInit' : Generates grids for the map
'DI_Map' : Generates star surface map according to starspot parameters (such as longitude, latitude, radius and contrast)
'DI_Prf' : Generates spectral line profiles according to map
Now I want to obtain the surface map over the generated and noised line profiles. I use scipy.optimize.minimize (TNC method) for obtain the surface map. I use 'DI_func' as function in minimize. But 'minimize' is so slow. What is the problem. How can I speed this up.
Here is a modified version of DI_Prf, where is the major computation time during the execution of DI_func:
def DI_Prf(grid, star, map, phase=None, vv=None, vr=None, nonoise=None):
# velocity array
if vv is not None:
nv = len(vv)
else:
nv = int(np.ceil(2.0 * star['vrange'] / star['vstep']))
vv = -star['vrange'] + np.arange(nv, dtype=float) * star['vstep']
# phase array
if phase is None:
phase = np.arange(star['nphases'], dtype=float) / star['nphases']
# velocity correction for each phase
vr = np.zeros(star['nphases'], dtype=float) if vr == None else None
# fixed trigonometric quantities
cosi = np.cos(np.deg2rad(star['incl'])); sini = np.sin(np.deg2rad(star['incl']))
coslat = np.cos(grid['lat']); sinlat = np.sin(grid['lat'])
# FWHM to Gaussian sigma
sigm = star['fwhm'] / np.sqrt(8.0 * np.log(2.0))
isig = (-0.5 / sigm ** 2)
# initialize line profile and integrated field arrays
prf = np.zeros((nv, len(phase)), dtype=float)
# gradient if called with 5 - variable input
grad = np.zeros((nv, len(phase), grid['ntot']), dtype=float)
# phase loop
for i in range(len(phase)):
coslon = np.cos(grid['lon'] + 2.0 * np.pi * phase[i])
sinlon = np.sin(grid['lon'] + 2.0 * np.pi * phase[i])
mu = sinlat * cosi + coslat * sini * coslon
ivis = np.argwhere(mu > 0.).T[0]
dv = -sinlon[ivis] * coslat[ivis] * star['vsini']
avis = grid['area'][ivis] * mu[ivis] * (1.0 - star['limbd'] + star['limbd'] * mu[ivis])
if star['type'] == 0:
wgt = avis * map[ivis]
wgtn = sum(wgt)
#for j in range(nv):
# plc = 1.0 - star['d'] * np.exp(isig * (vv[j] + dv - vr[i]) ** 2)
# prf[j][i] = sum(wgt * plc) / wgtn
# grad[j][i][ivis] = avis * plc / wgtn - avis * prf[j][i] / wgtn
plc = 1.0 - star['d'] * np.exp(isig * (vv[:, np.newaxis] + dv[np.newaxis, :] - vr[i]) ** 2)
prf[:, i] = np.sum(wgt * plc, axis=1) / wgtn
grad[:, i, ivis] = avis * plc / wgtn - (avis[:, np.newaxis]*prf[:, i]).T / wgtn
elif star['type'] == 1:
wgt = avis
wgtn = sum(wgt)
for j in range(nv): # to be modified too
plc = 1.0 - map[ivis] * star['d'] * np.exp(isig * (vv[j] + dv - vr[i]) ** 2)
prf[j][i] = sum(wgt * plc) / wgtn
grad[j][i][ivis] = -wgt / wgtn * star['d'] * np.exp(isig * (vv[j] + dv - vr[i]) ** 2)
# output structure
syn = {'v': vv, 'phase': phase, 'prf': prf}
# add noise
if star['snr'] != -1 and nonoise != None:
#for i in range(star['nphases']):
obs = syn['prf'] + np.random.standard_normal(size=syn['prf'].shape) / star['snr']
syn['obs'] = obs
return syn, grad
It reduces the time by 3:
%%timeit
syn, grad = DI_Prf(grid, star, cmap, phase=obs['phase'], vv=obs['v'])
# 127 ms ± 2.61 ms per loop (mean ± std. dev. of 7 runs, 10 loops each)
# 40.7 ms ± 683 µs per loop (mean ± std. dev. of 7 runs, 10 loops each)
The main idea with Numpy is to not use loops, but work with multidimensional array, and use the broadcasting capabilities.
For instance:
fchi = 0.0
for i in range(star['nphases']):
fchi = fchi + sign * sum((syn['prf'][:, i] - obs['obs'][:, i]) ** 2 / er ** 2) / nv
could be replaced with:
fchi = sign / nv / er ** 2 * np.sum( np.sum((syn['prf'] - obs['obs']) ** 2, axis=1 ) )
same for np.random.standard_normal(size=syn['prf'].shape)
It's not a big improvement here because star['nphases'] is small, but it is relatively important for the other axis. You could go further and remove the for loop over the phases in DI_Prf but it requires some thinking