Merge pull request #2050 from GiacomoPope/fq_default_ctx_randtest

Introduce `fq_default_ctx_init_randtest()`

Author: fredrik-johansson

doc/source/fq_default.rst

@@ -104,10 +104,10 @@ Context Management
 
     Prints the context information to ``stdout``.
 
-.. function:: void fq_default_ctx_randtest(fq_default_ctx_t ctx)
+.. function:: void fq_default_ctx_init_randtest(fq_default_ctx_t ctx, flint_rand_t state)
 
-    Initializes ``ctx`` to a random finite field.  Assumes that
-    ``fq_default_ctx_init`` has not been called on ``ctx`` already.
+    Initializes ``ctx`` to a random finite field using one of the five internal representations.
+    Assumes that ``fq_default_ctx_init`` has not been called on ``ctx`` already.
 
 .. function:: void fq_default_get_coeff_fmpz(fmpz_t c, fq_default_t op, slong n, const fq_default_ctx_t ctx)
 

src/fq_default.h

@@ -229,6 +229,7 @@ int fq_default_ctx_fprint(FILE * file, const fq_default_ctx_t ctx);
 #endif
 
 void fq_default_ctx_print(const fq_default_ctx_t ctx);
+void fq_default_ctx_init_randtest(fq_default_ctx_t ctx, flint_rand_t state);
 
 /* Memory management  *********************************************************/
 

src/fq_default/ctx.c

@@ -199,3 +199,43 @@ void fq_default_ctx_modulus(fmpz_mod_poly_t p, const fq_default_ctx_t ctx)
         fmpz_mod_poly_set(p, FQ_DEFAULT_CTX_FQ(ctx)->modulus, mod);
     }
 }
+
+/* Create a random fq_default_ctx picked from the five internal representations */
+void fq_default_ctx_init_randtest(fq_default_ctx_t ctx, flint_rand_t state)
+{
+    fmpz_t prime;
+    slong deg;
+
+    /* Select a context type [1,...,5] */
+    int ctx_type = 1 + n_randint(state, 5);
+    switch (ctx_type)
+    {
+        /* Create GF(p^d) for FQ_ZECH context */
+        case FQ_DEFAULT_FQ_ZECH:
+            fmpz_randprime(prime, state, 2 + n_randint(state, 3), 1);
+            deg = 1 + n_randint(state, 3);
+            break;
+        /* Create GF(p^d) for FQ_NMOD context */
+        case FQ_DEFAULT_FQ_NMOD:
+            fmpz_randprime(prime, state, 2 + n_randint(state, 29), 1);
+            deg = 1 + n_randint(state, 15);
+            break;
+        /* Create GF(p^d) for FQ context */
+        case FQ_DEFAULT_FQ:
+            fmpz_randprime(prime, state, 2 + n_randint(state, 62), 1);
+            deg = 1 + n_randint(state, 7);
+            break;
+        /* Create GF(p) for NMOD context */
+        case FQ_DEFAULT_NMOD:
+            fmpz_randprime(prime, state, 2 + n_randint(state, 29), 1);
+            deg = 1;
+            break;
+        /* Create GF(p) for FMPZ_MOD context */
+        case FQ_DEFAULT_FMPZ_MOD:
+            fmpz_randprime(prime, state, 2 + n_randint(state, 62), 1);
+            deg = 1;
+            break;
+        default: FLINT_UNREACHABLE;
+    }
+    fq_default_ctx_init_type(ctx, prime, deg, "a", ctx_type);
+}

src/fq_default/test/t-init.c

@@ -81,5 +81,17 @@ TEST_FUNCTION_START(fq_default_init, state)
         fmpz_clear(p);
     }
 
+    for (i = 0; i < 100 * flint_test_multiplier(); i++)
+    {
+        fq_default_ctx_t ctx;
+        fq_default_t fq;
+
+        fq_default_ctx_init_randtest(ctx, state);
+        fq_default_init(fq, ctx);
+        fq_default_randtest(fq, state, ctx);
+        fq_default_clear(fq, ctx);
+        fq_default_ctx_clear(ctx);
+    }
+
     TEST_FUNCTION_END(state);
 }