docs of new floats routines and added them to VM target too

compiler/res/prog8lib/virtual/floats.p8

@@ -80,6 +80,20 @@ sub atan(float value) -> float {
     }}
 }
 
+; two-argument arctangent that returns an angle in the correct quadrant
+; for the signs of x and y, normalized to the range [0, 2π]
+sub atan2(float y, float x) -> float {
+    float atn = atan(y / x)
+    if x < 0 atn += π
+    if atn < 0 atn += 2*π
+    return atn
+}
+
+; reciprocal functions
+sub secant(float value) -> float { return 1.0 / cos(value) }
+sub csc(float value)    -> float { return 1.0 / sin(value) }
+sub cot(float value)    -> float { return 1.0 / tan(value) }
+
 sub ln(float value) -> float {
     %ir {{
         loadm.f fr0,floats.ln.value

docs/source/libraries.rst

@@ -382,12 +382,22 @@ point variables.  This includes ``print_f``, the routine used to print floating
 ``atan (x)``
     Arctangent.
 
+``atan2 (y, x)``
+    Two-argument arctangent that returns an angle in the correct quadrant
+    for the signs of x and y, normalized to the range [0, 2π]
+
 ``ceil (x)``
     Rounds the floating point up to an integer towards positive infinity.
 
 ``cos (x)``
     Cosine.
 
+``cot (x)``
+    Cotangent: 1/tan(x)
+
+``csc (x)``
+    Cosecant: 1/sin(x)
+
 ``deg (x)``
     Radians to degrees.
 
@@ -426,6 +436,9 @@ point variables.  This includes ``print_f``, the routine used to print floating
 ``sin (x)``
     Sine.
 
+``secant (x)``
+    Secant: 1/cos(x)
+
 ``tan (x)``
     Tangent.