diff --git a/ext/numo/tiny_linalg/blas/gemm.hpp b/ext/numo/tiny_linalg/blas/gemm.hpp
index 550bb79..11462e9 100644
--- a/ext/numo/tiny_linalg/blas/gemm.hpp
+++ b/ext/numo/tiny_linalg/blas/gemm.hpp
@@ -102,9 +102,9 @@ class Gemm {
 
     dtype alpha = kw_values[0] != Qundef ? Converter().to_dtype(kw_values[0]) : Converter().one();
     dtype beta = kw_values[1] != Qundef ? Converter().to_dtype(kw_values[1]) : Converter().zero();
-    enum CBLAS_ORDER order = kw_values[2] != Qundef ? get_cblas_order(kw_values[2]) : CblasRowMajor;
-    enum CBLAS_TRANSPOSE transa = kw_values[3] != Qundef ? get_cblas_trans(kw_values[3]) : CblasNoTrans;
-    enum CBLAS_TRANSPOSE transb = kw_values[4] != Qundef ? get_cblas_trans(kw_values[4]) : CblasNoTrans;
+    enum CBLAS_ORDER order = kw_values[2] != Qundef ? Util().get_cblas_order(kw_values[2]) : CblasRowMajor;
+    enum CBLAS_TRANSPOSE transa = kw_values[3] != Qundef ? Util().get_cblas_trans(kw_values[3]) : CblasNoTrans;
+    enum CBLAS_TRANSPOSE transb = kw_values[4] != Qundef ? Util().get_cblas_trans(kw_values[4]) : CblasNoTrans;
 
     narray_t* a_nary = NULL;
     GetNArray(a, a_nary);
@@ -172,52 +172,6 @@ class Gemm {
 
     return ret;
   };
-
-  static enum CBLAS_TRANSPOSE get_cblas_trans(VALUE val) {
-    const char* option_str = StringValueCStr(val);
-    enum CBLAS_TRANSPOSE res = CblasNoTrans;
-
-    if (std::strlen(option_str) > 0) {
-      switch (option_str[0]) {
-      case 'n':
-      case 'N':
-        res = CblasNoTrans;
-        break;
-      case 't':
-      case 'T':
-        res = CblasTrans;
-        break;
-      case 'c':
-      case 'C':
-        res = CblasConjTrans;
-        break;
-      }
-    }
-
-    RB_GC_GUARD(val);
-
-    return res;
-  }
-
-  static enum CBLAS_ORDER get_cblas_order(VALUE val) {
-    const char* option_str = StringValueCStr(val);
-
-    if (std::strlen(option_str) > 0) {
-      switch (option_str[0]) {
-      case 'r':
-      case 'R':
-        break;
-      case 'c':
-      case 'C':
-        rb_warn("Numo::TinyLinalg::BLAS.gemm does not support column major.");
-        break;
-      }
-    }
-
-    RB_GC_GUARD(val);
-
-    return CblasRowMajor;
-  }
 };
 
 } // namespace TinyLinalg
diff --git a/ext/numo/tiny_linalg/blas/gemv.hpp b/ext/numo/tiny_linalg/blas/gemv.hpp
index 70f9353..db547a8 100644
--- a/ext/numo/tiny_linalg/blas/gemv.hpp
+++ b/ext/numo/tiny_linalg/blas/gemv.hpp
@@ -94,8 +94,8 @@ class Gemv {
 
     dtype alpha = kw_values[0] != Qundef ? Converter().to_dtype(kw_values[0]) : Converter().one();
     dtype beta = kw_values[1] != Qundef ? Converter().to_dtype(kw_values[1]) : Converter().zero();
-    enum CBLAS_ORDER order = kw_values[2] != Qundef ? get_cblas_order(kw_values[2]) : CblasRowMajor;
-    enum CBLAS_TRANSPOSE trans = kw_values[3] != Qundef ? get_cblas_trans(kw_values[3]) : CblasNoTrans;
+    enum CBLAS_ORDER order = kw_values[2] != Qundef ? Util().get_cblas_order(kw_values[2]) : CblasRowMajor;
+    enum CBLAS_TRANSPOSE trans = kw_values[3] != Qundef ? Util().get_cblas_trans(kw_values[3]) : CblasNoTrans;
 
     narray_t* a_nary = NULL;
     GetNArray(a, a_nary);
@@ -160,52 +160,6 @@ class Gemv {
 
     return ret;
   }
-
-  static enum CBLAS_TRANSPOSE get_cblas_trans(VALUE val) {
-    const char* option_str = StringValueCStr(val);
-    enum CBLAS_TRANSPOSE res = CblasNoTrans;
-
-    if (std::strlen(option_str) > 0) {
-      switch (option_str[0]) {
-      case 'n':
-      case 'N':
-        res = CblasNoTrans;
-        break;
-      case 't':
-      case 'T':
-        res = CblasTrans;
-        break;
-      case 'c':
-      case 'C':
-        res = CblasConjTrans;
-        break;
-      }
-    }
-
-    RB_GC_GUARD(val);
-
-    return res;
-  }
-
-  static enum CBLAS_ORDER get_cblas_order(VALUE val) {
-    const char* option_str = StringValueCStr(val);
-
-    if (std::strlen(option_str) > 0) {
-      switch (option_str[0]) {
-      case 'r':
-      case 'R':
-        break;
-      case 'c':
-      case 'C':
-        rb_warn("Numo::TinyLinalg::BLAS.gemm does not support column major.");
-        break;
-      }
-    }
-
-    RB_GC_GUARD(val);
-
-    return CblasRowMajor;
-  }
 };
 
 } // namespace TinyLinalg
diff --git a/ext/numo/tiny_linalg/lapack/geqrf.hpp b/ext/numo/tiny_linalg/lapack/geqrf.hpp
index ec76c42..c990aa9 100644
--- a/ext/numo/tiny_linalg/lapack/geqrf.hpp
+++ b/ext/numo/tiny_linalg/lapack/geqrf.hpp
@@ -61,7 +61,7 @@ class GeQrf {
     ID kw_table[1] = { rb_intern("order") };
     VALUE kw_values[1] = { Qundef };
     rb_get_kwargs(kw_args, kw_table, 0, 1, kw_values);
-    const int matrix_layout = kw_values[0] != Qundef ? get_matrix_layout(kw_values[0]) : LAPACK_ROW_MAJOR;
+    const int matrix_layout = kw_values[0] != Qundef ? Util().get_matrix_layout(kw_values[0]) : LAPACK_ROW_MAJOR;
 
     if (CLASS_OF(a_vnary) != nary_dtype) {
       a_vnary = rb_funcall(nary_dtype, rb_intern("cast"), 1, a_vnary);
@@ -93,26 +93,6 @@ class GeQrf {
 
     return ret;
   }
-
-  static int get_matrix_layout(VALUE val) {
-    const char* option_str = StringValueCStr(val);
-
-    if (std::strlen(option_str) > 0) {
-      switch (option_str[0]) {
-      case 'r':
-      case 'R':
-        break;
-      case 'c':
-      case 'C':
-        rb_warn("Numo::TinyLinalg::Lapack.getrf does not support column major.");
-        break;
-      }
-    }
-
-    RB_GC_GUARD(val);
-
-    return LAPACK_ROW_MAJOR;
-  }
 };
 
 } // namespace TinyLinalg
diff --git a/ext/numo/tiny_linalg/lapack/gesv.hpp b/ext/numo/tiny_linalg/lapack/gesv.hpp
index 95e9e75..4b0deec 100644
--- a/ext/numo/tiny_linalg/lapack/gesv.hpp
+++ b/ext/numo/tiny_linalg/lapack/gesv.hpp
@@ -71,7 +71,7 @@ class GeSv {
 
     rb_get_kwargs(kw_args, kw_table, 0, 1, kw_values);
 
-    const int matrix_layout = kw_values[0] != Qundef ? get_matrix_layout(kw_values[0]) : LAPACK_ROW_MAJOR;
+    const int matrix_layout = kw_values[0] != Qundef ? Util().get_matrix_layout(kw_values[0]) : LAPACK_ROW_MAJOR;
 
     if (CLASS_OF(a_vnary) != nary_dtype) {
       a_vnary = rb_funcall(nary_dtype, rb_intern("cast"), 1, a_vnary);
@@ -123,26 +123,6 @@ class GeSv {
 
     return ret;
   }
-
-  static int get_matrix_layout(VALUE val) {
-    const char* option_str = StringValueCStr(val);
-
-    if (std::strlen(option_str) > 0) {
-      switch (option_str[0]) {
-      case 'r':
-      case 'R':
-        break;
-      case 'c':
-      case 'C':
-        rb_warn("Numo::TinyLinalg::Lapack.gesv does not support column major.");
-        break;
-      }
-    }
-
-    RB_GC_GUARD(val);
-
-    return LAPACK_ROW_MAJOR;
-  }
 };
 
 } // namespace TinyLinalg
diff --git a/ext/numo/tiny_linalg/lapack/getrf.hpp b/ext/numo/tiny_linalg/lapack/getrf.hpp
index cc25780..088218a 100644
--- a/ext/numo/tiny_linalg/lapack/getrf.hpp
+++ b/ext/numo/tiny_linalg/lapack/getrf.hpp
@@ -61,7 +61,7 @@ class GeTrf {
     ID kw_table[1] = { rb_intern("order") };
     VALUE kw_values[1] = { Qundef };
     rb_get_kwargs(kw_args, kw_table, 0, 1, kw_values);
-    const int matrix_layout = kw_values[0] != Qundef ? get_matrix_layout(kw_values[0]) : LAPACK_ROW_MAJOR;
+    const int matrix_layout = kw_values[0] != Qundef ? Util().get_matrix_layout(kw_values[0]) : LAPACK_ROW_MAJOR;
 
     if (CLASS_OF(a_vnary) != nary_dtype) {
       a_vnary = rb_funcall(nary_dtype, rb_intern("cast"), 1, a_vnary);
@@ -93,26 +93,6 @@ class GeTrf {
 
     return ret;
   }
-
-  static int get_matrix_layout(VALUE val) {
-    const char* option_str = StringValueCStr(val);
-
-    if (std::strlen(option_str) > 0) {
-      switch (option_str[0]) {
-      case 'r':
-      case 'R':
-        break;
-      case 'c':
-      case 'C':
-        rb_warn("Numo::TinyLinalg::Lapack.getrf does not support column major.");
-        break;
-      }
-    }
-
-    RB_GC_GUARD(val);
-
-    return LAPACK_ROW_MAJOR;
-  }
 };
 
 } // namespace TinyLinalg
diff --git a/ext/numo/tiny_linalg/lapack/getri.hpp b/ext/numo/tiny_linalg/lapack/getri.hpp
index dc56357..491213a 100644
--- a/ext/numo/tiny_linalg/lapack/getri.hpp
+++ b/ext/numo/tiny_linalg/lapack/getri.hpp
@@ -57,7 +57,7 @@ class GeTri {
     ID kw_table[1] = { rb_intern("order") };
     VALUE kw_values[1] = { Qundef };
     rb_get_kwargs(kw_args, kw_table, 0, 1, kw_values);
-    const int matrix_layout = kw_values[0] != Qundef ? get_matrix_layout(kw_values[0]) : LAPACK_ROW_MAJOR;
+    const int matrix_layout = kw_values[0] != Qundef ? Util().get_matrix_layout(kw_values[0]) : LAPACK_ROW_MAJOR;
 
     if (CLASS_OF(a_vnary) != nary_dtype) {
       a_vnary = rb_funcall(nary_dtype, rb_intern("cast"), 1, a_vnary);
@@ -102,26 +102,6 @@ class GeTri {
 
     return ret;
   }
-
-  static int get_matrix_layout(VALUE val) {
-    const char* option_str = StringValueCStr(val);
-
-    if (std::strlen(option_str) > 0) {
-      switch (option_str[0]) {
-      case 'r':
-      case 'R':
-        break;
-      case 'c':
-      case 'C':
-        rb_warn("Numo::TinyLinalg::Lapack.getri does not support column major.");
-        break;
-      }
-    }
-
-    RB_GC_GUARD(val);
-
-    return LAPACK_ROW_MAJOR;
-  }
 };
 
 } // namespace TinyLinalg
diff --git a/ext/numo/tiny_linalg/lapack/hegv.hpp b/ext/numo/tiny_linalg/lapack/hegv.hpp
index 9049da0..b9a43ae 100644
--- a/ext/numo/tiny_linalg/lapack/hegv.hpp
+++ b/ext/numo/tiny_linalg/lapack/hegv.hpp
@@ -63,10 +63,10 @@ class HeGv {
     ID kw_table[4] = { rb_intern("itype"), rb_intern("jobz"), rb_intern("uplo"), rb_intern("order") };
     VALUE kw_values[4] = { Qundef, Qundef, Qundef, Qundef };
     rb_get_kwargs(kw_args, kw_table, 0, 4, kw_values);
-    const lapack_int itype = kw_values[0] != Qundef ? get_itype(kw_values[0]) : 1;
-    const char jobz = kw_values[1] != Qundef ? get_jobz(kw_values[1]) : 'V';
-    const char uplo = kw_values[2] != Qundef ? get_uplo(kw_values[2]) : 'U';
-    const int matrix_layout = kw_values[3] != Qundef ? get_matrix_layout(kw_values[3]) : LAPACK_ROW_MAJOR;
+    const lapack_int itype = kw_values[0] != Qundef ? Util().get_itype(kw_values[0]) : 1;
+    const char jobz = kw_values[1] != Qundef ? Util().get_jobz(kw_values[1]) : 'V';
+    const char uplo = kw_values[2] != Qundef ? Util().get_uplo(kw_values[2]) : 'U';
+    const int matrix_layout = kw_values[3] != Qundef ? Util().get_matrix_layout(kw_values[3]) : LAPACK_ROW_MAJOR;
 
     if (CLASS_OF(a_vnary) != nary_dtype) {
       a_vnary = rb_funcall(nary_dtype, rb_intern("cast"), 1, a_vnary);
@@ -116,52 +116,6 @@ class HeGv {
 
     return ret;
   }
-
-  static lapack_int get_itype(VALUE val) {
-    const lapack_int itype = NUM2INT(val);
-
-    if (itype != 1 && itype != 2 && itype != 3) {
-      rb_raise(rb_eArgError, "itype must be 1, 2 or 3");
-    }
-
-    return itype;
-  }
-
-  static char get_jobz(VALUE val) {
-    const char jobz = NUM2CHR(val);
-
-    if (jobz != 'n' && jobz != 'N' && jobz != 'v' && jobz != 'V') {
-      rb_raise(rb_eArgError, "jobz must be 'N' or 'V'");
-    }
-
-    return jobz;
-  }
-
-  static char get_uplo(VALUE val) {
-    const char uplo = NUM2CHR(val);
-
-    if (uplo != 'u' && uplo != 'U' && uplo != 'l' && uplo != 'L') {
-      rb_raise(rb_eArgError, "uplo must be 'U' or 'L'");
-    }
-
-    return uplo;
-  }
-
-  static int get_matrix_layout(VALUE val) {
-    const char option = NUM2CHR(val);
-
-    switch (option) {
-    case 'r':
-    case 'R':
-      break;
-    case 'c':
-    case 'C':
-      rb_warn("Numo::TinyLinalg::Lapack.sygv does not support column major.");
-      break;
-    }
-
-    return LAPACK_ROW_MAJOR;
-  }
 };
 
 } // namespace TinyLinalg
diff --git a/ext/numo/tiny_linalg/lapack/hegvd.hpp b/ext/numo/tiny_linalg/lapack/hegvd.hpp
index 8b0cf94..f7674da 100644
--- a/ext/numo/tiny_linalg/lapack/hegvd.hpp
+++ b/ext/numo/tiny_linalg/lapack/hegvd.hpp
@@ -63,10 +63,10 @@ class HeGvd {
     ID kw_table[4] = { rb_intern("itype"), rb_intern("jobz"), rb_intern("uplo"), rb_intern("order") };
     VALUE kw_values[4] = { Qundef, Qundef, Qundef, Qundef };
     rb_get_kwargs(kw_args, kw_table, 0, 4, kw_values);
-    const lapack_int itype = kw_values[0] != Qundef ? get_itype(kw_values[0]) : 1;
-    const char jobz = kw_values[1] != Qundef ? get_jobz(kw_values[1]) : 'V';
-    const char uplo = kw_values[2] != Qundef ? get_uplo(kw_values[2]) : 'U';
-    const int matrix_layout = kw_values[3] != Qundef ? get_matrix_layout(kw_values[3]) : LAPACK_ROW_MAJOR;
+    const lapack_int itype = kw_values[0] != Qundef ? Util().get_itype(kw_values[0]) : 1;
+    const char jobz = kw_values[1] != Qundef ? Util().get_jobz(kw_values[1]) : 'V';
+    const char uplo = kw_values[2] != Qundef ? Util().get_uplo(kw_values[2]) : 'U';
+    const int matrix_layout = kw_values[3] != Qundef ? Util().get_matrix_layout(kw_values[3]) : LAPACK_ROW_MAJOR;
 
     if (CLASS_OF(a_vnary) != nary_dtype) {
       a_vnary = rb_funcall(nary_dtype, rb_intern("cast"), 1, a_vnary);
@@ -116,52 +116,6 @@ class HeGvd {
 
     return ret;
   }
-
-  static lapack_int get_itype(VALUE val) {
-    const lapack_int itype = NUM2INT(val);
-
-    if (itype != 1 && itype != 2 && itype != 3) {
-      rb_raise(rb_eArgError, "itype must be 1, 2 or 3");
-    }
-
-    return itype;
-  }
-
-  static char get_jobz(VALUE val) {
-    const char jobz = NUM2CHR(val);
-
-    if (jobz != 'n' && jobz != 'N' && jobz != 'v' && jobz != 'V') {
-      rb_raise(rb_eArgError, "jobz must be 'N' or 'V'");
-    }
-
-    return jobz;
-  }
-
-  static char get_uplo(VALUE val) {
-    const char uplo = NUM2CHR(val);
-
-    if (uplo != 'u' && uplo != 'U' && uplo != 'l' && uplo != 'L') {
-      rb_raise(rb_eArgError, "uplo must be 'U' or 'L'");
-    }
-
-    return uplo;
-  }
-
-  static int get_matrix_layout(VALUE val) {
-    const char option = NUM2CHR(val);
-
-    switch (option) {
-    case 'r':
-    case 'R':
-      break;
-    case 'c':
-    case 'C':
-      rb_warn("Numo::TinyLinalg::Lapack.sygvd does not support column major.");
-      break;
-    }
-
-    return LAPACK_ROW_MAJOR;
-  }
 };
 
 } // namespace TinyLinalg
diff --git a/ext/numo/tiny_linalg/lapack/hegvx.hpp b/ext/numo/tiny_linalg/lapack/hegvx.hpp
index de5162e..6b3462d 100644
--- a/ext/numo/tiny_linalg/lapack/hegvx.hpp
+++ b/ext/numo/tiny_linalg/lapack/hegvx.hpp
@@ -70,15 +70,15 @@ class HeGvx {
                        rb_intern("vl"), rb_intern("vu"), rb_intern("il"), rb_intern("iu"), rb_intern("order") };
     VALUE kw_values[9] = { Qundef, Qundef, Qundef, Qundef, Qundef, Qundef, Qundef, Qundef, Qundef };
     rb_get_kwargs(kw_args, kw_table, 0, 9, kw_values);
-    const lapack_int itype = kw_values[0] != Qundef ? get_itype(kw_values[0]) : 1;
-    const char jobz = kw_values[1] != Qundef ? get_jobz(kw_values[1]) : 'V';
-    const char range = kw_values[2] != Qundef ? get_range(kw_values[2]) : 'A';
-    const char uplo = kw_values[3] != Qundef ? get_uplo(kw_values[3]) : 'U';
+    const lapack_int itype = kw_values[0] != Qundef ? Util().get_itype(kw_values[0]) : 1;
+    const char jobz = kw_values[1] != Qundef ? Util().get_jobz(kw_values[1]) : 'V';
+    const char range = kw_values[2] != Qundef ? Util().get_range(kw_values[2]) : 'A';
+    const char uplo = kw_values[3] != Qundef ? Util().get_uplo(kw_values[3]) : 'U';
     const rtype vl = kw_values[4] != Qundef ? NUM2DBL(kw_values[4]) : 0.0;
     const rtype vu = kw_values[5] != Qundef ? NUM2DBL(kw_values[5]) : 0.0;
     const lapack_int il = kw_values[6] != Qundef ? NUM2INT(kw_values[6]) : 0;
     const lapack_int iu = kw_values[7] != Qundef ? NUM2INT(kw_values[7]) : 0;
-    const int matrix_layout = kw_values[8] != Qundef ? get_matrix_layout(kw_values[8]) : LAPACK_ROW_MAJOR;
+    const int matrix_layout = kw_values[8] != Qundef ? Util().get_matrix_layout(kw_values[8]) : LAPACK_ROW_MAJOR;
 
     if (CLASS_OF(a_vnary) != nary_dtype) {
       a_vnary = rb_funcall(nary_dtype, rb_intern("cast"), 1, a_vnary);
@@ -132,62 +132,6 @@ class HeGvx {
 
     return ret;
   }
-
-  static lapack_int get_itype(VALUE val) {
-    const lapack_int itype = NUM2INT(val);
-
-    if (itype != 1 && itype != 2 && itype != 3) {
-      rb_raise(rb_eArgError, "itype must be 1, 2 or 3");
-    }
-
-    return itype;
-  }
-
-  static char get_jobz(VALUE val) {
-    const char jobz = NUM2CHR(val);
-
-    if (jobz != 'N' && jobz != 'V') {
-      rb_raise(rb_eArgError, "jobz must be 'N' or 'V'");
-    }
-
-    return jobz;
-  }
-
-  static char get_range(VALUE val) {
-    const char range = NUM2CHR(val);
-
-    if (range != 'A' && range != 'V' && range != 'I') {
-      rb_raise(rb_eArgError, "range must be 'A', 'V' or 'I'");
-    }
-
-    return range;
-  }
-
-  static char get_uplo(VALUE val) {
-    const char uplo = NUM2CHR(val);
-
-    if (uplo != 'U' && uplo != 'L') {
-      rb_raise(rb_eArgError, "uplo must be 'U' or 'L'");
-    }
-
-    return uplo;
-  }
-
-  static int get_matrix_layout(VALUE val) {
-    const char option = NUM2CHR(val);
-
-    switch (option) {
-    case 'r':
-    case 'R':
-      break;
-    case 'c':
-    case 'C':
-      rb_warn("Numo::TinyLinalg::Lapack.hegvx does not support column major.");
-      break;
-    }
-
-    return LAPACK_ROW_MAJOR;
-  }
 };
 
 } // namespace TinyLinalg
diff --git a/ext/numo/tiny_linalg/lapack/orgqr.hpp b/ext/numo/tiny_linalg/lapack/orgqr.hpp
index 00e69ba..76ca7ce 100644
--- a/ext/numo/tiny_linalg/lapack/orgqr.hpp
+++ b/ext/numo/tiny_linalg/lapack/orgqr.hpp
@@ -49,7 +49,7 @@ class OrgQr {
     ID kw_table[1] = { rb_intern("order") };
     VALUE kw_values[1] = { Qundef };
     rb_get_kwargs(kw_args, kw_table, 0, 1, kw_values);
-    const int matrix_layout = kw_values[0] != Qundef ? get_matrix_layout(kw_values[0]) : LAPACK_ROW_MAJOR;
+    const int matrix_layout = kw_values[0] != Qundef ? Util().get_matrix_layout(kw_values[0]) : LAPACK_ROW_MAJOR;
 
     if (CLASS_OF(a_vnary) != nary_dtype) {
       a_vnary = rb_funcall(nary_dtype, rb_intern("cast"), 1, a_vnary);
@@ -90,26 +90,6 @@ class OrgQr {
 
     return ret;
   }
-
-  static int get_matrix_layout(VALUE val) {
-    const char* option_str = StringValueCStr(val);
-
-    if (std::strlen(option_str) > 0) {
-      switch (option_str[0]) {
-      case 'r':
-      case 'R':
-        break;
-      case 'c':
-      case 'C':
-        rb_warn("Numo::TinyLinalg::Lapack.getrf does not support column major.");
-        break;
-      }
-    }
-
-    RB_GC_GUARD(val);
-
-    return LAPACK_ROW_MAJOR;
-  }
 };
 
 } // namespace TinyLinalg
diff --git a/ext/numo/tiny_linalg/lapack/sygv.hpp b/ext/numo/tiny_linalg/lapack/sygv.hpp
index fa60c7f..c829b74 100644
--- a/ext/numo/tiny_linalg/lapack/sygv.hpp
+++ b/ext/numo/tiny_linalg/lapack/sygv.hpp
@@ -54,10 +54,10 @@ class SyGv {
     ID kw_table[4] = { rb_intern("itype"), rb_intern("jobz"), rb_intern("uplo"), rb_intern("order") };
     VALUE kw_values[4] = { Qundef, Qundef, Qundef, Qundef };
     rb_get_kwargs(kw_args, kw_table, 0, 4, kw_values);
-    const lapack_int itype = kw_values[0] != Qundef ? get_itype(kw_values[0]) : 1;
-    const char jobz = kw_values[1] != Qundef ? get_jobz(kw_values[1]) : 'V';
-    const char uplo = kw_values[2] != Qundef ? get_uplo(kw_values[2]) : 'U';
-    const int matrix_layout = kw_values[3] != Qundef ? get_matrix_layout(kw_values[3]) : LAPACK_ROW_MAJOR;
+    const lapack_int itype = kw_values[0] != Qundef ? Util().get_itype(kw_values[0]) : 1;
+    const char jobz = kw_values[1] != Qundef ? Util().get_jobz(kw_values[1]) : 'V';
+    const char uplo = kw_values[2] != Qundef ? Util().get_uplo(kw_values[2]) : 'U';
+    const int matrix_layout = kw_values[3] != Qundef ? Util().get_matrix_layout(kw_values[3]) : LAPACK_ROW_MAJOR;
 
     if (CLASS_OF(a_vnary) != nary_dtype) {
       a_vnary = rb_funcall(nary_dtype, rb_intern("cast"), 1, a_vnary);
@@ -107,52 +107,6 @@ class SyGv {
 
     return ret;
   }
-
-  static lapack_int get_itype(VALUE val) {
-    const lapack_int itype = NUM2INT(val);
-
-    if (itype != 1 && itype != 2 && itype != 3) {
-      rb_raise(rb_eArgError, "itype must be 1, 2 or 3");
-    }
-
-    return itype;
-  }
-
-  static char get_jobz(VALUE val) {
-    const char jobz = NUM2CHR(val);
-
-    if (jobz != 'n' && jobz != 'N' && jobz != 'v' && jobz != 'V') {
-      rb_raise(rb_eArgError, "jobz must be 'N' or 'V'");
-    }
-
-    return jobz;
-  }
-
-  static char get_uplo(VALUE val) {
-    const char uplo = NUM2CHR(val);
-
-    if (uplo != 'u' && uplo != 'U' && uplo != 'l' && uplo != 'L') {
-      rb_raise(rb_eArgError, "uplo must be 'U' or 'L'");
-    }
-
-    return uplo;
-  }
-
-  static int get_matrix_layout(VALUE val) {
-    const char option = NUM2CHR(val);
-
-    switch (option) {
-    case 'r':
-    case 'R':
-      break;
-    case 'c':
-    case 'C':
-      rb_warn("Numo::TinyLinalg::Lapack.sygv does not support column major.");
-      break;
-    }
-
-    return LAPACK_ROW_MAJOR;
-  }
 };
 
 } // namespace TinyLinalg
diff --git a/ext/numo/tiny_linalg/lapack/sygvd.hpp b/ext/numo/tiny_linalg/lapack/sygvd.hpp
index bc32d24..002d7b7 100644
--- a/ext/numo/tiny_linalg/lapack/sygvd.hpp
+++ b/ext/numo/tiny_linalg/lapack/sygvd.hpp
@@ -54,10 +54,10 @@ class SyGvd {
     ID kw_table[4] = { rb_intern("itype"), rb_intern("jobz"), rb_intern("uplo"), rb_intern("order") };
     VALUE kw_values[4] = { Qundef, Qundef, Qundef, Qundef };
     rb_get_kwargs(kw_args, kw_table, 0, 4, kw_values);
-    const lapack_int itype = kw_values[0] != Qundef ? get_itype(kw_values[0]) : 1;
-    const char jobz = kw_values[1] != Qundef ? get_jobz(kw_values[1]) : 'V';
-    const char uplo = kw_values[2] != Qundef ? get_uplo(kw_values[2]) : 'U';
-    const int matrix_layout = kw_values[3] != Qundef ? get_matrix_layout(kw_values[3]) : LAPACK_ROW_MAJOR;
+    const lapack_int itype = kw_values[0] != Qundef ? Util().get_itype(kw_values[0]) : 1;
+    const char jobz = kw_values[1] != Qundef ? Util().get_jobz(kw_values[1]) : 'V';
+    const char uplo = kw_values[2] != Qundef ? Util().get_uplo(kw_values[2]) : 'U';
+    const int matrix_layout = kw_values[3] != Qundef ? Util().get_matrix_layout(kw_values[3]) : LAPACK_ROW_MAJOR;
 
     if (CLASS_OF(a_vnary) != nary_dtype) {
       a_vnary = rb_funcall(nary_dtype, rb_intern("cast"), 1, a_vnary);
@@ -107,52 +107,6 @@ class SyGvd {
 
     return ret;
   }
-
-  static lapack_int get_itype(VALUE val) {
-    const lapack_int itype = NUM2INT(val);
-
-    if (itype != 1 && itype != 2 && itype != 3) {
-      rb_raise(rb_eArgError, "itype must be 1, 2 or 3");
-    }
-
-    return itype;
-  }
-
-  static char get_jobz(VALUE val) {
-    const char jobz = NUM2CHR(val);
-
-    if (jobz != 'n' && jobz != 'N' && jobz != 'v' && jobz != 'V') {
-      rb_raise(rb_eArgError, "jobz must be 'N' or 'V'");
-    }
-
-    return jobz;
-  }
-
-  static char get_uplo(VALUE val) {
-    const char uplo = NUM2CHR(val);
-
-    if (uplo != 'u' && uplo != 'U' && uplo != 'l' && uplo != 'L') {
-      rb_raise(rb_eArgError, "uplo must be 'U' or 'L'");
-    }
-
-    return uplo;
-  }
-
-  static int get_matrix_layout(VALUE val) {
-    const char option = NUM2CHR(val);
-
-    switch (option) {
-    case 'r':
-    case 'R':
-      break;
-    case 'c':
-    case 'C':
-      rb_warn("Numo::TinyLinalg::Lapack.sygvd does not support column major.");
-      break;
-    }
-
-    return LAPACK_ROW_MAJOR;
-  }
 };
 
 } // namespace TinyLinalg
diff --git a/ext/numo/tiny_linalg/lapack/sygvx.hpp b/ext/numo/tiny_linalg/lapack/sygvx.hpp
index b9ef7aa..cbfee51 100644
--- a/ext/numo/tiny_linalg/lapack/sygvx.hpp
+++ b/ext/numo/tiny_linalg/lapack/sygvx.hpp
@@ -69,15 +69,15 @@ class SyGvx {
                        rb_intern("vl"), rb_intern("vu"), rb_intern("il"), rb_intern("iu"), rb_intern("order") };
     VALUE kw_values[9] = { Qundef, Qundef, Qundef, Qundef, Qundef, Qundef, Qundef, Qundef, Qundef };
     rb_get_kwargs(kw_args, kw_table, 0, 9, kw_values);
-    const lapack_int itype = kw_values[0] != Qundef ? get_itype(kw_values[0]) : 1;
-    const char jobz = kw_values[1] != Qundef ? get_jobz(kw_values[1]) : 'V';
-    const char range = kw_values[2] != Qundef ? get_range(kw_values[2]) : 'A';
-    const char uplo = kw_values[3] != Qundef ? get_uplo(kw_values[3]) : 'U';
+    const lapack_int itype = kw_values[0] != Qundef ? Util().get_itype(kw_values[0]) : 1;
+    const char jobz = kw_values[1] != Qundef ? Util().get_jobz(kw_values[1]) : 'V';
+    const char range = kw_values[2] != Qundef ? Util().get_range(kw_values[2]) : 'A';
+    const char uplo = kw_values[3] != Qundef ? Util().get_uplo(kw_values[3]) : 'U';
     const dtype vl = kw_values[4] != Qundef ? NUM2DBL(kw_values[4]) : 0.0;
     const dtype vu = kw_values[5] != Qundef ? NUM2DBL(kw_values[5]) : 0.0;
     const lapack_int il = kw_values[6] != Qundef ? NUM2INT(kw_values[6]) : 0;
     const lapack_int iu = kw_values[7] != Qundef ? NUM2INT(kw_values[7]) : 0;
-    const int matrix_layout = kw_values[8] != Qundef ? get_matrix_layout(kw_values[8]) : LAPACK_ROW_MAJOR;
+    const int matrix_layout = kw_values[8] != Qundef ? Util().get_matrix_layout(kw_values[8]) : LAPACK_ROW_MAJOR;
 
     if (CLASS_OF(a_vnary) != nary_dtype) {
       a_vnary = rb_funcall(nary_dtype, rb_intern("cast"), 1, a_vnary);
@@ -131,62 +131,6 @@ class SyGvx {
 
     return ret;
   }
-
-  static lapack_int get_itype(VALUE val) {
-    const lapack_int itype = NUM2INT(val);
-
-    if (itype != 1 && itype != 2 && itype != 3) {
-      rb_raise(rb_eArgError, "itype must be 1, 2 or 3");
-    }
-
-    return itype;
-  }
-
-  static char get_jobz(VALUE val) {
-    const char jobz = NUM2CHR(val);
-
-    if (jobz != 'N' && jobz != 'V') {
-      rb_raise(rb_eArgError, "jobz must be 'N' or 'V'");
-    }
-
-    return jobz;
-  }
-
-  static char get_range(VALUE val) {
-    const char range = NUM2CHR(val);
-
-    if (range != 'A' && range != 'V' && range != 'I') {
-      rb_raise(rb_eArgError, "range must be 'A', 'V' or 'I'");
-    }
-
-    return range;
-  }
-
-  static char get_uplo(VALUE val) {
-    const char uplo = NUM2CHR(val);
-
-    if (uplo != 'U' && uplo != 'L') {
-      rb_raise(rb_eArgError, "uplo must be 'U' or 'L'");
-    }
-
-    return uplo;
-  }
-
-  static int get_matrix_layout(VALUE val) {
-    const char option = NUM2CHR(val);
-
-    switch (option) {
-    case 'r':
-    case 'R':
-      break;
-    case 'c':
-    case 'C':
-      rb_warn("Numo::TinyLinalg::Lapack.sygvx does not support column major.");
-      break;
-    }
-
-    return LAPACK_ROW_MAJOR;
-  }
 };
 
 } // namespace TinyLinalg
diff --git a/ext/numo/tiny_linalg/lapack/ungqr.hpp b/ext/numo/tiny_linalg/lapack/ungqr.hpp
index 19e815e..7d1198e 100644
--- a/ext/numo/tiny_linalg/lapack/ungqr.hpp
+++ b/ext/numo/tiny_linalg/lapack/ungqr.hpp
@@ -49,7 +49,7 @@ class UngQr {
     ID kw_table[1] = { rb_intern("order") };
     VALUE kw_values[1] = { Qundef };
     rb_get_kwargs(kw_args, kw_table, 0, 1, kw_values);
-    const int matrix_layout = kw_values[0] != Qundef ? get_matrix_layout(kw_values[0]) : LAPACK_ROW_MAJOR;
+    const int matrix_layout = kw_values[0] != Qundef ? Util().get_matrix_layout(kw_values[0]) : LAPACK_ROW_MAJOR;
 
     if (CLASS_OF(a_vnary) != nary_dtype) {
       a_vnary = rb_funcall(nary_dtype, rb_intern("cast"), 1, a_vnary);
@@ -90,26 +90,6 @@ class UngQr {
 
     return ret;
   }
-
-  static int get_matrix_layout(VALUE val) {
-    const char* option_str = StringValueCStr(val);
-
-    if (std::strlen(option_str) > 0) {
-      switch (option_str[0]) {
-      case 'r':
-      case 'R':
-        break;
-      case 'c':
-      case 'C':
-        rb_warn("Numo::TinyLinalg::Lapack.getrf does not support column major.");
-        break;
-      }
-    }
-
-    RB_GC_GUARD(val);
-
-    return LAPACK_ROW_MAJOR;
-  }
 };
 
 } // namespace TinyLinalg
diff --git a/ext/numo/tiny_linalg/tiny_linalg.cpp b/ext/numo/tiny_linalg/tiny_linalg.cpp
index 31a7af4..0b95f88 100644
--- a/ext/numo/tiny_linalg/tiny_linalg.cpp
+++ b/ext/numo/tiny_linalg/tiny_linalg.cpp
@@ -1,10 +1,13 @@
 #include "tiny_linalg.hpp"
+
+#include "converter.hpp"
+#include "util.hpp"
+
 #include "blas/dot.hpp"
 #include "blas/dot_sub.hpp"
 #include "blas/gemm.hpp"
 #include "blas/gemv.hpp"
 #include "blas/nrm2.hpp"
-#include "converter.hpp"
 #include "lapack/geqrf.hpp"
 #include "lapack/gesdd.hpp"
 #include "lapack/gesv.hpp"
diff --git a/ext/numo/tiny_linalg/util.hpp b/ext/numo/tiny_linalg/util.hpp
new file mode 100644
index 0000000..3721034
--- /dev/null
+++ b/ext/numo/tiny_linalg/util.hpp
@@ -0,0 +1,100 @@
+namespace TinyLinalg {
+
+class Util {
+public:
+  static lapack_int get_itype(VALUE val) {
+    const lapack_int itype = NUM2INT(val);
+
+    if (itype != 1 && itype != 2 && itype != 3) {
+      rb_raise(rb_eArgError, "itype must be 1, 2 or 3");
+    }
+
+    return itype;
+  }
+
+  static char get_jobz(VALUE val) {
+    const char jobz = NUM2CHR(val);
+
+    if (jobz != 'N' && jobz != 'V') {
+      rb_raise(rb_eArgError, "jobz must be 'N' or 'V'");
+    }
+
+    return jobz;
+  }
+
+  static char get_range(VALUE val) {
+    const char range = NUM2CHR(val);
+
+    if (range != 'A' && range != 'V' && range != 'I') {
+      rb_raise(rb_eArgError, "range must be 'A', 'V' or 'I'");
+    }
+
+    return range;
+  }
+
+  static char get_uplo(VALUE val) {
+    const char uplo = NUM2CHR(val);
+
+    if (uplo != 'U' && uplo != 'L') {
+      rb_raise(rb_eArgError, "uplo must be 'U' or 'L'");
+    }
+
+    return uplo;
+  }
+
+  static int get_matrix_layout(VALUE val) {
+    const char option = NUM2CHR(val);
+
+    switch (option) {
+    case 'r':
+    case 'R':
+      break;
+    case 'c':
+    case 'C':
+      rb_warn("Numo::TinyLinalg does not support column major.");
+      break;
+    }
+
+    return LAPACK_ROW_MAJOR;
+  }
+
+  static enum CBLAS_TRANSPOSE get_cblas_trans(VALUE val) {
+    const char option = NUM2CHR(val);
+    enum CBLAS_TRANSPOSE res = CblasNoTrans;
+
+    switch (option) {
+    case 'n':
+    case 'N':
+      res = CblasNoTrans;
+      break;
+    case 't':
+    case 'T':
+      res = CblasTrans;
+      break;
+    case 'c':
+    case 'C':
+      res = CblasConjTrans;
+      break;
+    }
+
+    return res;
+  }
+
+  static enum CBLAS_ORDER get_cblas_order(VALUE val) {
+    const char option = NUM2CHR(val);
+
+    switch (option) {
+    case 'r':
+    case 'R':
+      break;
+    case 'c':
+    case 'C':
+      rb_warn("Numo::TinyLinalg does not support column major.");
+      break;
+    }
+
+    return CblasRowMajor;
+  }
+};
+
+} // namespace TinyLinalg