1 files changed, 7 insertions, 1 deletions
diff --git a/docs/bqn.js b/docs/bqn.js
index edac15b5..8e6d6398 100644
--- a/docs/bqn.js
+++ b/docs/bqn.js
@@ -599,10 +599,16 @@ let primitives = dynsys(state => {
   return list(gl.map((g,i) => list([g,rt[i]])));
 });
 
+let mathfn = f => {
+  f.prim=null; let p=runtime[61](f,0); // ⚇
+  return f!==Math.atan2 && f!==Math.hypot
+    ? ((x,w) => {if ( has(w)) throw Error("Left argument not allowed"); return p(x);})
+    : ((x,w) => {if (!has(w)) throw Error("Left argument required");    return p(x,w);});
+}
 let trig = "cos cosh sin sinh tan tanh".split(" ");
 let mathns = obj2ns(Math,
   trig.concat(trig.map(n=>"a"+n),"LN10 LN2 LOG10E LOG2E cbrt expm1 hypot log10 log1p log2 round trunc atan2".split(" ")),
-  f=>typeof f==="function"?(f.prim=null,runtime[61](f,0)):f
+  f=>typeof f==="function"?mathfn(f):f
 );
 trig.map((_,i)=>{let f=mathns[i],g=mathns[i+trig.length]; f.inverse=g; g.inverse=f;});