canSumWithSelfAndMulWithFloat

auto a = [ 1.0f, 2, 3 ];
assertEq( a.mean, 2.0f );

static assert( !__traits(compiles,mean(a[0])) );
static assert( !__traits(compiles,[1,2,3].mean) );
static assert(  __traits(compiles,[1.0f,2,3].mean) );

import std.conv : to;

assertEq( iota(11).map!(a=>to!float(a)).mean, 5 );

import des.math.linear.vector;

auto a = [ vec3(1,2,3), vec3(2,3,4), vec3(3,4,5) ];
assertEq( a.mean, vec3(2,3,4) );