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import os import matplotlib.pyplot as plt import numpy as np import scipy os.chdir('/home/vg/Downloads/projects/ex17') os.getcwd() def f(x): return [x[1]-x[0]**3-2*x[0]**2+1,x[1]+x[0]**2-1] tol=0.1 a,b=-2,2 x=np.linspace(-3,2,5000) y1=x**3+2*x**2-1 y2=-x**2+1 fig,ax=plt.subplots(figsize=(8,4)) ax.plot(x,y1,'k',lw=1.5) ax.plot(x,y2,'k',lw=1.5) sol1=scipy.optimize.fsolve(f,[-2,2]) sol2=scipy.optimize.fsolve(f,[1,-1]) sol3=scipy.optimize.fsolve(f,[-2,-5]) sols=[sol1,sol2,sol3] colors=['r','b','g'] for idx,s in enumerate(sols): ax.plot(s[0],s[1],colors[idx]+'*',markersize=15) for m in np.linspace(-4,3,80): for n in np.linspace(-20,20,40): x_guess=[m,n] sol=scipy.optimize.fsolve(f,x_guess) idx = (abs(sols-sol)**2).sum(axis=1).argmin() ax.plot(x_guess[0],x_guess[1],colors[idx]+'.') ax.set_title("Convergence of different initial guesses to different solutions") plt.savefig("example17.png", dpi=100) plt.show() plt.close() <img class=" wp-image-102 aligncenter" src="https://gantovnik.com/bio-tips/wp-content/uploads/2018/12/example17.png" alt="example17" width="616" height="308" /> |
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