small changes based on code review

src/include/units/bits/unit_text.h

@@ -35,12 +35,12 @@ constexpr auto ratio_text()
       return txt + basic_fixed_string("]");
     }
     else if constexpr (Ratio::den == 1) {
-      return txt + basic_fixed_string(" x 10") + superscript<Ratio::exp>() +
+      return txt + basic_fixed_string(" \u00D7 10") + superscript<Ratio::exp>() +
           basic_fixed_string("]");
     }
     else {
       return txt + basic_fixed_string("/") + regular<Ratio::den>() +
-          basic_fixed_string(" x 10") + superscript<Ratio::exp>() +
+          basic_fixed_string(" \u00D7 10") + superscript<Ratio::exp>() +
           basic_fixed_string("]");
     }
   }

src/include/units/physical/si/prefixes.h

@@ -23,31 +23,32 @@
 #pragma once
 
 #include <units/prefix.h>
-#include <ratio>
 
 namespace units::si {
 
 struct prefix : prefix_type {};
 
-// TODO Remove dependency on std::ratio
-
-// clang-format off
-struct atto   : units::prefix<atto,   prefix, "a",      ratio<1, 1, -18>> {}; // std::atto::den>> {};
-struct femto  : units::prefix<femto,  prefix, "f",      ratio<1, 1, -15>> {}; // std::femto::den>> {};
-struct pico   : units::prefix<pico,   prefix, "p",      ratio<1, 1, -12>> {}; // std::pico::den>> {};
-struct nano   : units::prefix<nano,   prefix, "n",      ratio<1, 1,  -9>> {}; // std::nano::den>> {};
-struct micro  : units::prefix<micro,  prefix, "\u00b5", ratio<1, 1,  -6>> {}; // std::micro::den>> {};
-struct milli  : units::prefix<milli,  prefix, "m",      ratio<1, 1,  -3>> {}; // std::milli::den>> {};
-struct centi  : units::prefix<centi,  prefix, "c",      ratio<1, 1,  -2>> {}; // std::centi::den>> {};
-struct deci   : units::prefix<deci,   prefix, "d",      ratio<1, 1,  -1>> {}; // std::deci::den>> {};
-struct deca   : units::prefix<deca,   prefix, "da",     ratio<1, 1,   1>> {}; // std::deca::num>> {};
-struct hecto  : units::prefix<hecto,  prefix, "h",      ratio<1, 1,   2>> {}; // std::hecto::num>> {};
-struct kilo   : units::prefix<kilo,   prefix, "k",      ratio<1, 1,   3>> {}; // std::kilo::num>> {};
-struct mega   : units::prefix<mega,   prefix, "M",      ratio<1, 1,   6>> {}; // std::mega::num>> {};
-struct giga   : units::prefix<giga,   prefix, "G",      ratio<1, 1,   9>> {}; // std::giga::num>> {};
-struct tera   : units::prefix<tera,   prefix, "T",      ratio<1, 1,  12>> {}; // std::tera::num>> {};
-struct peta   : units::prefix<peta,   prefix, "P",      ratio<1, 1,  15>> {}; // std::peta::num>> {};
-struct exa    : units::prefix<exa,    prefix, "E",      ratio<1, 1,  18>> {}; // std::exa::num>> {};
 // clang-format off
+struct yocto  : units::prefix<yocto,  prefix, "y",      ratio<1, 1, -24>> {};
+struct zepto  : units::prefix<zepto,  prefix, "z",      ratio<1, 1, -21>> {};
+struct atto   : units::prefix<atto,   prefix, "a",      ratio<1, 1, -18>> {};
+struct femto  : units::prefix<femto,  prefix, "f",      ratio<1, 1, -15>> {};
+struct pico   : units::prefix<pico,   prefix, "p",      ratio<1, 1, -12>> {};
+struct nano   : units::prefix<nano,   prefix, "n",      ratio<1, 1,  -9>> {};
+struct micro  : units::prefix<micro,  prefix, "\u00b5", ratio<1, 1,  -6>> {};
+struct milli  : units::prefix<milli,  prefix, "m",      ratio<1, 1,  -3>> {};
+struct centi  : units::prefix<centi,  prefix, "c",      ratio<1, 1,  -2>> {};
+struct deci   : units::prefix<deci,   prefix, "d",      ratio<1, 1,  -1>> {};
+struct deca   : units::prefix<deca,   prefix, "da",     ratio<1, 1,   1>> {};
+struct hecto  : units::prefix<hecto,  prefix, "h",      ratio<1, 1,   2>> {};
+struct kilo   : units::prefix<kilo,   prefix, "k",      ratio<1, 1,   3>> {};
+struct mega   : units::prefix<mega,   prefix, "M",      ratio<1, 1,   6>> {};
+struct giga   : units::prefix<giga,   prefix, "G",      ratio<1, 1,   9>> {};
+struct tera   : units::prefix<tera,   prefix, "T",      ratio<1, 1,  12>> {};
+struct peta   : units::prefix<peta,   prefix, "P",      ratio<1, 1,  15>> {};
+struct exa    : units::prefix<exa,    prefix, "E",      ratio<1, 1,  18>> {};
+struct zetta  : units::prefix<zetta,  prefix, "Z",      ratio<1, 1,  21>> {};
+struct yotta  : units::prefix<yotta,  prefix, "Y",      ratio<1, 1,  24>> {};
+// clang-format on
 
 }  // namespace units::si

src/include/units/quantity.h

@@ -1,3 +1,4 @@
+
 // The MIT License (MIT)
 //
 // Copyright (c) 2018 Mateusz Pusz
@@ -32,7 +33,6 @@
 #endif
 
 #include <ostream>
-#include <iostream>
 
 namespace units {
 

test/unit_test/runtime/fmt_test.cpp

@@ -296,7 +296,7 @@ TEST_CASE("operator<< on a quantity", "[text][ostream][fmt]")
 
       SECTION("iostream")
       {
-        CHECK(stream.str() == "8 [1 x 10⁻²]m³");
+        CHECK(stream.str() == "8 [1 \u00D7 10⁻²]m³");
       }
 
       SECTION("fmt with default format {} on a quantity")
@@ -317,7 +317,7 @@ TEST_CASE("operator<< on a quantity", "[text][ostream][fmt]")
 
       SECTION("iostream")
       {
-        CHECK(stream.str() == "2 [6 x 10¹]Hz");
+        CHECK(stream.str() == "2 [6 \u00D7 10¹]Hz");
       }
 
       SECTION("fmt with default format {} on a quantity")
@@ -338,7 +338,7 @@ TEST_CASE("operator<< on a quantity", "[text][ostream][fmt]")
 
       SECTION("iostream")
       {
-        CHECK(stream.str() == "10 [1/6 x 10⁻¹]W");
+        CHECK(stream.str() == "10 [1/6 \u00D7 10⁻¹]W");
       }
 
       SECTION("fmt with default format {} on a quantity")
@@ -359,7 +359,7 @@ TEST_CASE("operator<< on a quantity", "[text][ostream][fmt]")
 
       SECTION("iostream")
       {
-        CHECK(stream.str() == "30 [1/6 x 10²]W");
+        CHECK(stream.str() == "30 [1/6 \u00D7 10²]W");
       }
 
       SECTION("fmt with default format {} on a quantity")
@@ -404,7 +404,7 @@ TEST_CASE("operator<< on a quantity", "[text][ostream][fmt]")
 
       SECTION("iostream")
       {
-        CHECK(stream.str() == "8 [1 x 10³]m⋅s");
+        CHECK(stream.str() == "8 [1 \u00D7 10³]m⋅s");
       }
 
       SECTION("fmt with default format {} on a quantity")
@@ -425,7 +425,7 @@ TEST_CASE("operator<< on a quantity", "[text][ostream][fmt]")
 
       SECTION("iostream")
       {
-        CHECK(stream.str() == "2 [6 x 10¹]kg/s");
+        CHECK(stream.str() == "2 [6 \u00D7 10¹]kg/s");
       }
 
       SECTION("fmt with default format {} on a quantity")
@@ -446,7 +446,7 @@ TEST_CASE("operator<< on a quantity", "[text][ostream][fmt]")
 
       SECTION("iostream")
       {
-        CHECK(stream.str() == "10 [1/6 x 10⁻¹]kg/s");
+        CHECK(stream.str() == "10 [1/6 \u00D7 10⁻¹]kg/s");
       }
 
       SECTION("fmt with default format {} on a quantity")
@@ -467,7 +467,7 @@ TEST_CASE("operator<< on a quantity", "[text][ostream][fmt]")
 
       SECTION("iostream")
       {
-        CHECK(stream.str() == "30 [6 x 10⁻²]1/m⋅s");
+        CHECK(stream.str() == "30 [6 \u00D7 10⁻²]1/m⋅s");
       }
 
       SECTION("fmt with default format {} on a quantity")