H11returns the value of the Hankel function of the first kind and order one ofx,H1(1)(x). For positive values ofx, the real component of the value returned containsJ1(x) and the imaginary component containsY1(x). For negative values ofx, the real component containsJ1(x) and the imaginary component contains -Y1(x).
Errors
H11causes an HTBasic error if its argument is not of type REAL. It also causes an error if the value ofxis near zero, since the imaginary component ofH1(1)(0) is -.