Less common mathematical functions defined in REF NUMBERS include:
phase(NUM) Returns the complex phase angle of NUM as a floating-point quantity. cis(REALANGLE) Returns the float-complex number cos(REALANGLE) +: sin(REALANGLE) arctan2(REAL_X, REAL_Y) -> REALANGLE Computes the arctangent of REAL_Y / REAL_X, but using the signs of the two numbers to derive quadrant information. sinh(ANGLE) cosh(ANGLE) tanh(ANGLE) These procedures compute the hyperbolic sine, hyperbolic cosine and hyperbolic tangent of ANGLE. The result is a floating-point, or a float-complex if ANGLE is complex. arcsinh(NUM) arccosh(NUM) arctanh(NUM) These procedures compute the hyperbolic arcsine, hyperbolic arccosine and hyperbolic arctangent of NUM. For NUM complex, the result is a float-complex. For NUM real, the result will be a real float, except in the following cases: arccosh: NUM < 1 arctanh: abs(NUM) > 1 For -arctanh-, it is an error if NUM = 1 or -1. linearfit(LIST) -> (M,C) The library LIB LINEARFIT makes available the procedure linearfit, which takes a list of pairs of numbers representing co-ordinates of points, works out the best straight line through the points, and returns its slope M, and its Y-intercept C. linearfit([% conspair(0,0), conspair(1.01, 0.98), conspair(1.85, 2.005), conspair(3.0, 3.0) %]) => ** 1.015095 0.009136 For vertical or nearly vertical lines it will produce an error.