26 lines
610 B
Python
26 lines
610 B
Python
#经典R-K，龙格-库塔法
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def ClassicRK(x0,y0,h,xk,fxy):
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k1=k2=k3=k4=0
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result = [(x0,y0)]
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while x0<=xk:
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k1 = fxy(x0,y0)
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k2 = fxy(x0+h/2,y0+h*k1/2)
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k3 = fxy(x0+h/2,y0+h*k2/2)
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k4 = fxy(x0+h,y0+h*k3)
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y0 += h*(k1+4*k2+k3)/6
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x0 += h
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result.append((x0,y0))
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return result
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if __name__=="__main__":
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x0 = 0
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y0 = -1
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fxy = lambda x,y: x + y
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real_fx = lambda x: -x-1
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h = 0.1
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xk = 2
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result = ClassicRK(x0, y0, h, xk, fxy)
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print("x\ty\t\treal_y")
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for x, y in result:
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print(f"{x:.2f}\t{y}\t{real_fx(x)}") |