31 lines
709 B
C
31 lines
709 B
C
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#include <math.h>
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float bessj1(x)
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float x;
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{
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float ax,z;
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double xx,y,ans,ans1,ans2;
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if ((ax=fabs(x)) < 8.0) {
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y=x*x;
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ans1=x*(72362614232.0+y*(-7895059235.0+y*(242396853.1
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+y*(-2972611.439+y*(15704.48260+y*(-30.16036606))))));
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ans2=144725228442.0+y*(2300535178.0+y*(18583304.74
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+y*(99447.43394+y*(376.9991397+y*1.0))));
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ans=ans1/ans2;
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} else {
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z=8.0/ax;
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y=z*z;
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xx=ax-2.356194491;
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ans1=1.0+y*(0.183105e-2+y*(-0.3516396496e-4
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+y*(0.2457520174e-5+y*(-0.240337019e-6))));
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ans2=0.04687499995+y*(-0.2002690873e-3
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+y*(0.8449199096e-5+y*(-0.88228987e-6
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+y*0.105787412e-6)));
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ans=sqrt(0.636619772/ax)*(cos(xx)*ans1-z*sin(xx)*ans2);
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if (x < 0.0) ans = -ans;
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}
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return ans;
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}
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