Improve docs for median (#294)

Author: jmh530

source/mir/math/stat.d

@@ -1229,9 +1229,16 @@ unittest
 /++
 Computes the median of `slice`.
 
+By default, if `F` is not floating point type or complex type, then the result
+will have a `double` type if `F` is implicitly convertible to a floating point 
+type or have a `cdouble` type if `F` is implicitly convertible to a complex type.
+
 Can also pass a boolean variable, `allowModify`, that allows the input slice to
 be modified. By default, a reference-counted copy is made. 
 
+Params:
+ F = output type
+ allowModify = Allows the input slice to be modified, default is false
 Returns:
  the median of the slice
 
@@ -1240,8 +1247,16 @@ See_also:
 +/
 template median(F, bool allowModify = false)
 {
- F median(Iterator, size_t N, SliceKind kind)(Slice!(Iterator, N, kind) slice)
+ /++
+ Params:
+ slice = slice
+ +/
+ meanType!F median(Iterator, size_t N, SliceKind kind)(Slice!(Iterator, N, kind) slice)
  {
+ static assert (!allowModify ||
+ isMutable!(DeepElementType!(Slice!(Iterator, N, kind))),
+ "allowModify must be false or the input must be mutable");
+ alias G = typeof(return);
  size_t len = slice.elementCount;
  assert(len > 0, "median: slice must have length greater than zero");
 
@@ -1253,9 +1268,9 @@ template median(F, bool allowModify = false)
  if (len > 2) {
  auto val = slice.rcslice.flattened;
  auto temp = val.lightScope;
- return .median!(F, true)(temp);
+ return .median!(G, true)(temp);
  } else {
- return mean!F(slice);
+ return mean!G(slice);
  }
  } else {
  import mir.ndslice.sorting: partitionAt;
@@ -1266,26 +1281,31 @@ template median(F, bool allowModify = false)
  size_t half_n = len / 2;
  partitionAt(temp, half_n);
  if (len % 2 == 1) {
- return cast(F) temp[half_n];
+ return cast(G) temp[half_n];
  } else {
  //move largest value in first half of slice to half_n - 1
  partitionAt(temp[0 .. half_n], half_n - 1);
- return (temp[half_n - 1] + temp[half_n]) / cast(F) 2;
+ return (temp[half_n - 1] + temp[half_n]) / cast(G) 2;
  }
  } else {
- return smallMedianImpl!(F)(temp);
+ return smallMedianImpl!(G)(temp);
  }
  }
  }
 }
 
-///
+/// ditto
 template median(bool allowModify = false)
 {
- sumType!(Slice!(Iterator, N, kind))
- median
- (Iterator, size_t N, SliceKind kind)(Slice!(Iterator, N, kind) slice) {
- return .median!(sumType!(Slice!(Iterator, N, kind)), allowModify)(slice.move);
+ /// ditto
+ meanType!(Slice!(Iterator, N, kind))
+ median(Iterator, size_t N, SliceKind kind)(Slice!(Iterator, N, kind) slice)
+ {
+ static assert (!allowModify ||
+ isMutable!(DeepElementType!(Slice!(Iterator, N, kind))),
+ "allowModify must be false or the input must be mutable");
+ alias F = typeof(return);
+ return .median!(F, allowModify)(slice.move);
  }
 }
 
@@ -1356,7 +1376,7 @@ unittest
 }
 
 /++
-For integral slices, pass output type as template parameter to ensure output
+For integral slices, can pass output type as template parameter to ensure output
 type is correct
 +/
 version(mir_test)
@@ -1366,7 +1386,11 @@ unittest
  import mir.ndslice.slice: sliced;
 
  auto x = [9, 1, 0, 2, 3, 4, 6, 8, 7, 10].sliced;
- assert(x.median!float == 5);
+ assert(x.median!float == 5f);
+
+ auto y = x.median;
+ assert(y == 5.0);
+ static assert(is(typeof(y) == double));
 }
 
 version(mir_test)