// Ceres Solver - A fast non-linear least squares minimizer
// Copyright 2012 Google Inc. All rights reserved. 
// http://code.google.com/p/ceres-solver/
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
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//   this list of conditions and the following disclaimer. 
// * Redistributions in binary form must reproduce the above copyright notice,
//   this list of conditions and the following disclaimer in the documentation
//   and/or other materials provided with the distribution. 
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//   used to endorse or promote products derived from this software without
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//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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//
// Author: sameeragarwal@google.com (Sameer Agarwal)
//
// Utility routines for validating arrays. 
//
// These are useful for detecting two common class of errors. 
//
// 1.  Uninitialized memory - where the user for some reason did not
// compute part of an array, but the code expects it. 
//
// 2.  Numerical failure while computing the cost/residual/jacobian,
// e.g. NaN, infinities etc.  This is particularly useful since the
// automatic differentiation code does computations that are not
// evident to the user and can silently generate hard to debug errors. 

#ifndef CERES_INTERNAL_ARRAY_UTILS_H_
#define CERES_INTERNAL_ARRAY_UTILS_H_

#include "ceres/internal/port.h"

namespace ceres {
namespace internal {

// Fill the array x with an impossible value that the user code is
// never expected to compute. 
void InvalidateArray(int size, double* x);

// Check if all the entries of the array x are valid, i.e. all the
// values in the array should be finite and none of them should be
// equal to the "impossible" value used by InvalidateArray. 
bool IsArrayValid(int size, const double* x);

// If the array contains an invalid value, return the index for it,
// otherwise return size. 
int FindInvalidValue(const int size, const double* x);

// Utility routine to print an array of doubles to a string.  If the
// array pointer is NULL, it is treated as an array of zeros. 
void AppendArrayToString(const int size, const double* x, string* result);

extern const double kImpossibleValue;

}  // namespace internal
}  // namespace ceres

#endif  // CERES_INTERNAL_ARRAY_UTILS_H_
