externfloat A[], B[];externfloat MAXNUMF;floatchbevlf(float,float*,int);floatexpf(float),i1f(float),logf(float),sqrtf(float);floatk1f(float xx){float x, y;
x = xx;if( x <=2.0){
y = x * x -2.0;
y =logf(0.5f * x ) *i1f(x) +chbevlf( y, A,7) / x;return( y );}return(expf(-x) *chbevlf( (float)(8.0/x -2.0), B,10) /sqrtf(x) );}