22 lines
447 B
C
22 lines
447 B
C
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#include <math.h>
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float bessk1(float x)
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{
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float bessi1(float x);
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double y,ans;
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if (x <= 2.0) {
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y=x*x/4.0;
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ans=(log(x/2.0)*bessi1(x))+(1.0/x)*(1.0+y*(0.15443144
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+y*(-0.67278579+y*(-0.18156897+y*(-0.1919402e-1
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+y*(-0.110404e-2+y*(-0.4686e-4)))))));
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} else {
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y=2.0/x;
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ans=(exp(-x)/sqrt(x))*(1.25331414+y*(0.23498619
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+y*(-0.3655620e-1+y*(0.1504268e-1+y*(-0.780353e-2
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+y*(0.325614e-2+y*(-0.68245e-3)))))));
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}
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return ans;
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}
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