// SPDX-License-Identifier: Apache-2.0
// 
// Copyright 2015 Conrad Sanderson (http://conradsanderson.id.au)
// Copyright 2015 National ICT Australia (NICTA)
// 
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// http://www.apache.org/licenses/LICENSE-2.0
// 
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// ------------------------------------------------------------------------


#include <armadillo>
#include "catch.hpp"
#include "utils.hpp"

using namespace arma;


TEMPLATE_TEST_CASE("fn_diff_1", "[diff]", TEST_FLOAT_TYPES)
  {
  typedef TestType eT;
  
  Col<eT> a = square( linspace<Col<eT>>(1,5,6) );
  Row<eT> b = square( linspace<Row<eT>>(1,5,5) );
  
  Col<eT> a_diff_1 = { eT(2.2400), eT(3.5200), eT(4.8000), eT(6.0800), eT(7.3600) };
  Col<eT> a_diff_2 = { eT(1.2800), eT(1.2800), eT(1.2800), eT(1.2800) };
  Col<eT> a_diff_9;
  
  Row<eT> b_diff_1 = { eT(3), eT(5), eT(7), eT(9) };
  Row<eT> b_diff_2 = { eT(2), eT(2), eT(2) };
  Row<eT> b_diff_9;

  // significantly larger margin for low-precision because the errors can really add up!
  constexpr eT margin = is_blas_real<eT>::value ? eT(0.001) : eT(1.0);
  
  REQUIRE( eT(accu(abs(diff(a,0) - a       ))) == Approx(eT(0)).margin(margin) );
  REQUIRE( eT(accu(abs(diff(a  ) - a_diff_1))) == Approx(eT(0)).margin(margin) );
  REQUIRE( eT(accu(abs(diff(a,1) - a_diff_1))) == Approx(eT(0)).margin(margin) );
  REQUIRE( eT(accu(abs(diff(a,2) - a_diff_2))) == Approx(eT(0)).margin(margin) );
  REQUIRE( eT(accu(abs(diff(a,9) - a_diff_9))) == Approx(eT(0)).margin(margin) );
  
  REQUIRE( eT(accu(abs(diff(b,0) - b       ))) == Approx(eT(0)).margin(margin) );
  REQUIRE( eT(accu(abs(diff(b  ) - b_diff_1))) == Approx(eT(0)).margin(margin) );
  REQUIRE( eT(accu(abs(diff(b,1) - b_diff_1))) == Approx(eT(0)).margin(margin) );
  REQUIRE( eT(accu(abs(diff(b,2) - b_diff_2))) == Approx(eT(0)).margin(margin) );
  REQUIRE( eT(accu(abs(diff(b,9) - b_diff_9))) == Approx(eT(0)).margin(margin) );
  }



TEST_CASE("fn_diff_2", "[diff]")
  {
  mat A = 
    "\
     0.061198   0.201990   0.019678  -0.493936  -0.126745;\
     0.437242   0.058956  -0.149362  -0.045465   0.296153;\
    -0.492474  -0.031309   0.314156   0.419733   0.068317;\
     0.336352   0.411541   0.458476  -0.393139  -0.135040;\
     0.239585  -0.428913  -0.406953  -0.291020  -0.353768;\
    ";

  mat A_diff1_0 = 
    "\
     0.376044  -0.143034  -0.169040   0.448471   0.422898;\
    -0.929716  -0.090265   0.463518   0.465198  -0.227836;\
     0.828826   0.442850   0.144320  -0.812872  -0.203357;\
    -0.096767  -0.840454  -0.865429   0.102119  -0.218728;\
    ";

  mat A_diff2_0 = 
    "\
    -1.305760   0.052769   0.632558   0.016727  -0.650734;\
     1.758542   0.533115  -0.319198  -1.278070   0.024479;\
    -0.925593  -1.283304  -1.009749   0.914991  -0.015371;\
    ";

  mat A_diff3_0 = 
    "\
     3.064302   0.480346  -0.951756  -1.294797   0.675213;\
    -2.684135  -1.816419  -0.690551   2.193061  -0.039850;\
    ";

  mat A_diff1_1 = 
    "\
     0.140792  -0.182312  -0.513614   0.367191;\
    -0.378286  -0.208318   0.103897   0.341618;\
     0.461165   0.345465   0.105577  -0.351416;\
     0.075189   0.046935  -0.851615   0.258099;\
    -0.668498   0.021960   0.115933  -0.062748;\
    ";

  mat A_diff2_1 = 
    "\
    -0.323104  -0.331302   0.880805;\
     0.169968   0.312215   0.237721;\
    -0.115700  -0.239888  -0.456993;\
    -0.028254  -0.898550   1.109714;\
     0.690458   0.093973  -0.178681;\
    ";

  mat A_diff3_1 = 
    "\
    -0.0081980   1.2121070;\
     0.1422470  -0.0744940;\
    -0.1241880  -0.2171050;\
    -0.8702960   2.0082640;\
    -0.5964850  -0.2726540;\
    ";
    
  REQUIRE( accu(abs(diff(A,0) - A        )) == Approx(0.0).margin(0.001) );
  REQUIRE( accu(abs(diff(A  ) - A_diff1_0)) == Approx(0.0).margin(0.001) );
  REQUIRE( accu(abs(diff(A,1) - A_diff1_0)) == Approx(0.0).margin(0.001) );
  REQUIRE( accu(abs(diff(A,2) - A_diff2_0)) == Approx(0.0).margin(0.001) );
  REQUIRE( accu(abs(diff(A,3) - A_diff3_0)) == Approx(0.0).margin(0.001) );
  
  REQUIRE( accu(abs(diff(A,0,0) - A        )) == Approx(0.0).margin(0.001) );
  REQUIRE( accu(abs(diff(A,1,0) - A_diff1_0)) == Approx(0.0).margin(0.001) );
  REQUIRE( accu(abs(diff(A,2,0) - A_diff2_0)) == Approx(0.0).margin(0.001) );
  REQUIRE( accu(abs(diff(A,3,0) - A_diff3_0)) == Approx(0.0).margin(0.001) );
  
  REQUIRE( accu(abs(diff(A,0,1) - A        )) == Approx(0.0).margin(0.001) );
  REQUIRE( accu(abs(diff(A,1,1) - A_diff1_1)) == Approx(0.0).margin(0.001) );
  REQUIRE( accu(abs(diff(A,2,1) - A_diff2_1)) == Approx(0.0).margin(0.001) );
  REQUIRE( accu(abs(diff(A,3,1) - A_diff3_1)) == Approx(0.0).margin(0.001) );
  }