functions in dawson.i -

             any_in(left,x,right, mask, xx, a,aa, b,bb, c,cc  
 
    return the number of elements of the array X which are in the  
    interval LEFT < X <= RIGHT.  Also return MASK, which has the  
    shape of X and is 1 where X is in the interval and 0 otherwise,  
    and XX = X(where(MASK)).  Up to three optional arrays A, B, and C  
    of the same shape as X may be supplied; the arrays AA, BB, and CC  
    analogous to XX are returned.  LEFT or RIGHT may be [] for the  
    interval to extend to infinity on the corresponding side.  
    LEFT and/or RIGHT may be arrays as long as they are conformable  
    with X.  

             dawson(x)  
 
    return Dawson's integral, exp(-x^2)*integral[0 to x](exp(t^2)*dt)  
    maximum is dawson(0.9241388730) = 0.5410442246  
    inflection point is dawson(1.5019752682) = 0.4276866160  

             erf(x)  
 
    return erf(x), 2./sqrt(pi) * integral[0 to x](exp(-t^2)*dt)  

             erfc(x)  
 
    return erfc(x), 2./sqrt(pi) * integral[x to infinity](exp(-t^2)*dt)  

             merge_n(val1,mask1, val2,mask2, ...)  
 
    return array with shape of MASKi (which must all have same shape)  
    and values VALi where MASKi is true.  Unspecified values will be  
    zero; the data type of the result is the data type of the first  
    non-nil VALi.  Each VALi must be a 1D array of length sum(MASKi!=0).