Generalize view and size functions

stan/math/prim/err.hpp

@@ -43,6 +43,7 @@
 #include <stan/math/prim/err/check_symmetric.hpp>
 #include <stan/math/prim/err/check_unit_vector.hpp>
 #include <stan/math/prim/err/check_vector.hpp>
+#include <stan/math/prim/err/check_vector_index.hpp>
 #include <stan/math/prim/err/constraint_tolerance.hpp>
 #include <stan/math/prim/err/domain_error.hpp>
 #include <stan/math/prim/err/domain_error_vec.hpp>

stan/math/prim/err/check_column_index.hpp

@@ -17,18 +17,16 @@ namespace math {
  * <code>stan::error_index::value</code>. This function will
  * throw an <code>std::out_of_range</code> exception if
  * the index is out of bounds.
- * @tparam T_y Type of scalar
- * @tparam R number of rows or Eigen::Dynamic
- * @tparam C number of columns or Eigen::Dynamic
+ * @tparam T_y Type of matrix
  * @param function Function name (for error messages)
  * @param name Variable name (for error messages)
  * @param y matrix to test
  * @param i column index to check
  * @throw <code>std::out_of_range</code> if index is an invalid column
  */
-template <typename T_y, int R, int C>
+template <typename T_y, typename = require_eigen_t<T_y>>
 inline void check_column_index(const char* function, const char* name,
-                               const Eigen::Matrix<T_y, R, C>& y, size_t i) {
+                               const T_y& y, size_t i) {
   if (i >= stan::error_index::value
       && i < static_cast<size_t>(y.cols()) + stan::error_index::value) {
     return;

stan/math/prim/err/check_row_index.hpp

@@ -14,18 +14,16 @@ namespace math {
  * Check if the specified index is a valid row of the matrix
  * This check is 1-indexed by default. This behavior can be changed
  * by setting <code>stan::error_index::value</code>.
- * @tparam T Scalar type
- * @tparam R number of rows or Eigen::Dynamic
- * @tparam C number of columns or Eigen::Dynamic
+ * @tparam T Matrix type
  * @param function Function name (for error messages)
  * @param name Variable name (for error messages)
  * @param y matrix to test
  * @param i row index to check
  * @throw <code>std::out_of_range</code> if the index is out of range.
  */
-template <typename T_y, int R, int C>
+template <typename T_y, typename = require_eigen_t<T_y>>
 inline void check_row_index(const char* function, const char* name,
-                            const Eigen::Matrix<T_y, R, C>& y, size_t i) {
+                            const T_y& y, size_t i) {
   if (i >= stan::error_index::value
       && i < static_cast<size_t>(y.rows()) + stan::error_index::value) {
     return;

stan/math/prim/err/check_vector_index.hpp

@@ -0,0 +1,40 @@
+#ifndef STAN_MATH_PRIM_ERR_CHECK_VECTOR_INDEX_HPP
+#define STAN_MATH_PRIM_ERR_CHECK_VECTOR_INDEX_HPP
+
+#include <stan/math/prim/meta.hpp>
+#include <stan/math/prim/err/out_of_range.hpp>
+#include <stan/math/prim/fun/Eigen.hpp>
+#include <sstream>
+#include <string>
+
+namespace stan {
+namespace math {
+
+/**
+ * Check if the specified index is a valid element of the row or column vector
+ * This check is 1-indexed by default. This behavior can be changed
+ * by setting <code>stan::error_index::value</code>.
+ * @tparam T Vector type
+ * @param function Function name (for error messages)
+ * @param name Variable name (for error messages)
+ * @param y vector to test
+ * @param i row index to check
+ * @throw <code>std::out_of_range</code> if the index is out of range.
+ */
+template <typename T, typename = require_eigen_vector_t<T>>
+inline void check_vector_index(const char* function, const char* name,
+                               const T& y, size_t i) {
+  if (i >= stan::error_index::value
+      && i < static_cast<size_t>(y.size()) + stan::error_index::value) {
+    return;
+  }
+
+  std::stringstream msg;
+  msg << " for size of " << name;
+  std::string msg_str(msg.str());
+  out_of_range(function, y.rows(), i, msg_str.c_str());
+}
+
+}  // namespace math
+}  // namespace stan
+#endif

stan/math/prim/fun/col.hpp

@@ -14,17 +14,16 @@ namespace math {
  * This is equivalent to calling <code>m.col(i - 1)</code> and
  * assigning the resulting template expression to a column vector.
  *
- * @tparam T type of elements in the matrix
+ * @tparam T type of the matrix
  * @param m Matrix.
  * @param j Column index (count from 1).
  * @return Specified column of the matrix.
  * @throw std::out_of_range if j is out of range.
  */
-template <typename T>
-inline Eigen::Matrix<T, Eigen::Dynamic, 1> col(
-    const Eigen::Matrix<T, Eigen::Dynamic, Eigen::Dynamic>& m, size_t j) {
+template <typename T, typename = require_eigen_t<T>>
+inline auto col(const T& m, size_t j) {
   check_column_index("col", "j", m, j);
-  return m.col(j - 1);
+  return m.col(j - 1).eval();
 }
 
 }  // namespace math

stan/math/prim/fun/cols.hpp

@@ -2,6 +2,7 @@
 #define STAN_MATH_PRIM_FUN_COLS_HPP
 
 #include <stan/math/prim/fun/Eigen.hpp>
+#include <stan/math/prim/meta.hpp>
 
 namespace stan {
 namespace math {
@@ -10,14 +11,12 @@ namespace math {
  * Return the number of columns in the specified
  * matrix, vector, or row vector.
  *
- * @tparam T type of elements in the matrix
- * @tparam R number of rows, can be Eigen::Dynamic
- * @tparam C number of columns, can be Eigen::Dynamic
+ * @tparam T type of the matrix
  * @param[in] m Input matrix, vector, or row vector.
  * @return Number of columns.
  */
-template <typename T, int R, int C>
-inline int cols(const Eigen::Matrix<T, R, C>& m) {
+template <typename T, typename = require_eigen_t<T>>
+inline int cols(const T& m) {
   return m.cols();
 }
 

stan/math/prim/fun/diagonal.hpp

@@ -2,6 +2,7 @@
 #define STAN_MATH_PRIM_FUN_DIAGONAL_HPP
 
 #include <stan/math/prim/fun/Eigen.hpp>
+#include <stan/math/prim/meta.hpp>
 
 namespace stan {
 namespace math {
@@ -10,14 +11,13 @@ namespace math {
  * Return a column vector of the diagonal elements of the
  * specified matrix.  The matrix is not required to be square.
  *
- * @tparam T type of elements in the matrix
+ * @tparam T type of the matrix
  * @param m Specified matrix.
  * @return Diagonal of the matrix.
  */
-template <typename T>
-inline Eigen::Matrix<T, Eigen::Dynamic, 1> diagonal(
-    const Eigen::Matrix<T, Eigen::Dynamic, Eigen::Dynamic>& m) {
-  return m.diagonal();
+template <typename T, typename = require_eigen_t<T>>
+inline auto diagonal(const T& m) {
+  return m.diagonal().eval();
 }
 
 }  // namespace math

stan/math/prim/fun/dims.hpp

@@ -2,17 +2,18 @@
 #define STAN_MATH_PRIM_FUN_DIMS_HPP
 
 #include <stan/math/prim/fun/Eigen.hpp>
+#include <stan/math/prim/meta.hpp>
 #include <vector>
 
 namespace stan {
 namespace math {
 
-template <typename T>
+template <typename T, typename = require_stan_scalar_t<T>>
 inline void dims(const T& x, std::vector<int>& result) {
   /* no op */
 }
-template <typename T, int R, int C>
-inline void dims(const Eigen::Matrix<T, R, C>& x, std::vector<int>& result) {
+template <typename T, typename = require_eigen_t<T>, typename = void>
+inline void dims(const T& x, std::vector<int>& result) {
   result.push_back(x.rows());
   result.push_back(x.cols());
 }

stan/math/prim/fun/head.hpp

@@ -9,41 +9,21 @@ namespace stan {
 namespace math {
 
 /**
- * Return the specified number of elements as a vector
- * from the front of the specified vector.
+ * Return the specified number of elements as a vector or row vector (same as
+ * input) from the front of the specified vector or row vector.
  *
- * @tparam T type of elements in the vector
+ * @tparam T type of the vector
  * @param v Vector input.
  * @param n Size of return.
  * @return The first n elements of v.
  * @throw std::out_of_range if n is out of range.
  */
-template <typename T>
-inline Eigen::Matrix<T, Eigen::Dynamic, 1> head(
-    const Eigen::Matrix<T, Eigen::Dynamic, 1>& v, size_t n) {
+template <typename T, typename = require_eigen_vector_t<T>>
+inline auto head(const T& v, size_t n) {
   if (n != 0) {
-    check_row_index("head", "n", v, n);
+    check_vector_index("head", "n", v, n);
   }
-  return v.head(n);
-}
-
-/**
- * Return the specified number of elements as a row vector
- * from the front of the specified row vector.
- *
- * @tparam T type of elements in the vector
- * @param rv Row vector.
- * @param n Size of return row vector.
- * @return The first n elements of rv.
- * @throw std::out_of_range if n is out of range.
- */
-template <typename T>
-inline Eigen::Matrix<T, 1, Eigen::Dynamic> head(
-    const Eigen::Matrix<T, 1, Eigen::Dynamic>& rv, size_t n) {
-  if (n != 0) {
-    check_column_index("head", "n", rv, n);
-  }
-  return rv.head(n);
+  return v.head(n).eval();
 }
 
 /**
@@ -62,10 +42,7 @@ std::vector<T> head(const std::vector<T>& sv, size_t n) {
     check_std_vector_index("head", "n", sv, n);
   }
 
-  std::vector<T> s;
-  for (size_t i = 0; i < n; ++i) {
-    s.push_back(sv[i]);
-  }
+  std::vector<T> s(sv.begin(), sv.begin() + n);
   return s;
 }
 

stan/math/prim/fun/num_elements.hpp

@@ -2,6 +2,7 @@
 #define STAN_MATH_PRIM_FUN_NUM_ELEMENTS_HPP
 
 #include <stan/math/prim/fun/Eigen.hpp>
+#include <stan/math/prim/meta.hpp>
 #include <vector>
 
 namespace stan {
@@ -14,23 +15,21 @@ namespace math {
  * @param x Argument of primitive type.
  * @return 1
  */
-template <typename T>
+template <typename T, typename = require_stan_scalar_t<T>>
 inline int num_elements(const T& x) {
   return 1;
 }
 
 /**
  * Returns the size of the specified matrix.
  *
- * @tparam T type of elements in the matrix
- * @tparam R number of rows, can be Eigen::Dynamic
- * @tparam C number of columns, can be Eigen::Dynamic
+ * @tparam T type of the matrix
  *
  * @param m argument matrix
  * @return size of matrix
  */
-template <typename T, int R, int C>
-inline int num_elements(const Eigen::Matrix<T, R, C>& m) {
+template <typename T, typename = require_eigen_t<T>, typename = void>
+inline int num_elements(const T& m) {
   return m.size();
 }
 

stan/math/prim/fun/row.hpp

@@ -14,18 +14,17 @@ namespace math {
  * This is equivalent to calling <code>m.row(i - 1)</code> and
  * assigning the resulting template expression to a row vector.
  *
- * @tparam T type of elements in the matrix
+ * @tparam T type of the matrix
  * @param m Matrix.
  * @param i Row index (count from 1).
  * @return Specified row of the matrix.
  * @throw std::out_of_range if i is out of range.
  */
-template <typename T>
-inline Eigen::Matrix<T, 1, Eigen::Dynamic> row(
-    const Eigen::Matrix<T, Eigen::Dynamic, Eigen::Dynamic>& m, size_t i) {
+template <typename T, typename = require_eigen_t<T>>
+inline auto row(const T& m, size_t i) {
   check_row_index("row", "i", m, i);
 
-  return m.row(i - 1);
+  return m.row(i - 1).eval();
 }
 
 }  // namespace math

stan/math/prim/fun/rows.hpp

@@ -2,6 +2,7 @@
 #define STAN_MATH_PRIM_FUN_ROWS_HPP
 
 #include <stan/math/prim/fun/Eigen.hpp>
+#include <stan/math/prim/meta.hpp>
 
 namespace stan {
 namespace math {
@@ -10,15 +11,12 @@ namespace math {
  * Return the number of rows in the specified
  * matrix, vector, or row vector.
  *
- * @tparam T type of elements in the matrix
- * @tparam R number of rows, can be Eigen::Dynamic
- * @tparam C number of columns, can be Eigen::Dynamic
- *
+ * @tparam T type of the matrix
  * @param[in] m Input matrix, vector, or row vector.
  * @return Number of rows.
  */
-template <typename T, int R, int C>
-inline int rows(const Eigen::Matrix<T, R, C>& m) {
+template <typename T, typename = require_eigen_t<T>>
+inline int rows(const T& m) {
   return m.rows();
 }
 

stan/math/prim/fun/sub_col.hpp

@@ -10,23 +10,21 @@ namespace math {
 /**
  * Return a nrows x 1 subcolumn starting at (i-1, j-1).
  *
- * @tparam T type of elements in the matrix
+ * @tparam T type of the matrix
  * @param m Matrix.
  * @param i Starting row + 1.
  * @param j Starting column + 1.
  * @param nrows Number of rows in block.
  * @throw std::out_of_range if either index is out of range.
  */
-template <typename T>
-inline Eigen::Matrix<T, Eigen::Dynamic, 1> sub_col(
-    const Eigen::Matrix<T, Eigen::Dynamic, Eigen::Dynamic>& m, size_t i,
-    size_t j, size_t nrows) {
+template <typename T, typename = require_eigen_t<T>>
+inline auto sub_col(const T& m, size_t i, size_t j, size_t nrows) {
   check_row_index("sub_col", "i", m, i);
   if (nrows > 0) {
     check_row_index("sub_col", "i+nrows-1", m, i + nrows - 1);
   }
   check_column_index("sub_col", "j", m, j);
-  return m.block(i - 1, j - 1, nrows, 1);
+  return m.col(j - 1).segment(i - 1, nrows).eval();
 }
 
 }  // namespace math

stan/math/prim/fun/sub_row.hpp

@@ -10,23 +10,21 @@ namespace math {
 /**
  * Return a 1 x nrows subrow starting at (i-1, j-1).
  *
- * @tparam T type of elements in the matrix
+ * @tparam T type of the matrix
  * @param m Matrix Input matrix.
  * @param i Starting row + 1.
  * @param j Starting column + 1.
  * @param ncols Number of columns in block.
  * @throw std::out_of_range if either index is out of range.
  */
-template <typename T>
-inline Eigen::Matrix<T, 1, Eigen::Dynamic> sub_row(
-    const Eigen::Matrix<T, Eigen::Dynamic, Eigen::Dynamic>& m, size_t i,
-    size_t j, size_t ncols) {
+template <typename T, typename = require_eigen_t<T>>
+inline auto sub_row(const T& m, size_t i, size_t j, size_t ncols) {
   check_row_index("sub_row", "i", m, i);
   check_column_index("sub_row", "j", m, j);
   if (ncols > 0) {
     check_column_index("sub_col", "j+ncols-1", m, j + ncols - 1);
   }
-  return m.block(i - 1, j - 1, 1, ncols);
+  return m.row(i - 1).segment(j - 1, ncols).eval();
 }
 
 }  // namespace math