38 lines
1.2 KiB
Python
38 lines
1.2 KiB
Python
import math
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#正割法计算方程
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def SecantSolve(fx, x0, x1, err=1e-10, N0=100):
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count = 0
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print(f"k={count}: x{count}={x0}, f(x{count})={fx(x0)}")
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count += 1
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print(f"k={count}: x{count}={x1}, f(x{count})={fx(x1)}")
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count += 1
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while abs(x1 - x0) > err or abs(fx(x1)) > err:
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if fx(x1) == fx(x0):
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return None,0
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x2 = x1 - fx(x1) * (x1 - x0) / (fx(x1) - fx(x0))
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print(f"k={count}: x{count}={x2}, f(x{count})={fx(x2)}")
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count += 1
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if count > N0:
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return None,-1
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x0 = x1
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x1 = x2
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return x2,1
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if __name__ == "__main__":
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##############################################################################################################
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err = 1e-5 # 根的误差限 P148
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N0 = 100 # 最大迭代次数
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x0 = 0.3 # 初始值1
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x1 = 0.4 # 初始值2
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fx = lambda x: x**4 - 3*x + 1 #原函数
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result, status = SecantSolve(fx, x0, x1, err, N0)
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if status == 1:
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print(f"fx收敛 解为: {result}")
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elif status == -1:
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print("fx不收敛")
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else:
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print("分母为0，无法收敛") |