gh-36086: using python-style for-loops in modular folder
    
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This is converting some for-loops to python style instead of C-style.
Here, all of them in `modular` folder.

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URL: #36086
Reported by: Frédéric Chapoton
Reviewer(s): David Coudert

Author: Release Manager

src/sage/modular/arithgroup/congroup.pyx

@@ -132,7 +132,7 @@ def degeneracy_coset_representatives_gamma0(int N, int M, int t):
         dd = dd / g
         # Test if we've found a new coset representative.
         is_new = 1
-        for i from 0 <= i < k:
+        for i in range(k):
             j = 4*i
             if (R[j+1]*aa - R[j]*bb) % t == 0 and \
                (R[j+3]*cc - R[j+2]*dd) % Ndivt == 0:
@@ -237,7 +237,7 @@ def degeneracy_coset_representatives_gamma1(int N, int M, int t):
             continue
         # Test if we've found a new coset representative.
         is_new = 1
-        for i from 0 <= i < k:
+        for i in range(k):
             j = 4*i
             if (R[j] - aa) % t == 0 and \
                (R[j+1] - bb) % t == 0 and \
@@ -258,7 +258,7 @@ def degeneracy_coset_representatives_gamma1(int N, int M, int t):
 
     # Return the list left multiplied by T.
     S = []
-    for i from 0 <= i < k:
+    for i in range(k):
         j = 4*i
         S.append([R[j], R[j+1], R[j+2]*t, R[j+3]*t])
     sig_free(R)

src/sage/modular/modform/eis_series_cython.pyx

@@ -93,7 +93,7 @@ cpdef Ek_ZZ(int k, int prec=10):
         while True:
             continue_flag = 0
             # do the first p-1
-            for i from 0 < i < p:
+            for i in range(1, p):
                 ind += p
                 if (ind >= prec):
                     continue_flag = 1
@@ -215,7 +215,7 @@ cpdef eisenstein_series_poly(int k, int prec = 10) :
     mpz_clear(last_m1)
 
     fmpz_poly_set_coeff_mpz(res.poly, prec-1, val[prec-1])
-    for i from 1 <= i < prec - 1 :
+    for i in range(1, prec - 1):
         fmpz_poly_set_coeff_mpz(res.poly, i, val[i])
 
     fmpz_poly_scalar_mul_mpz(res.poly, res.poly, (<Integer>(a0.denominator())).value)

src/sage/modular/modform/l_series_gross_zagier_coeffs.pyx

@@ -68,7 +68,7 @@ def bqf_theta_series(Q, long bound, var=None):
     cdef long a, b, c
     a, b, c = Q
     cdef long* terms = bqf_theta_series_c(NULL, bound, a, b, c)
-    L = [terms[i] for i from 0 <= i <= bound]
+    L = [terms[i] for i in range(bound + 1)]
     sig_free(terms)
     return to_series(L, var)
 
@@ -85,13 +85,13 @@ cdef long* bqf_theta_series_c(long* terms, long bound, long a, long b, long c) e
         terms = <long*>check_calloc(1 + bound, sizeof(long))
 
     sig_on()
-    for x from -xmax <= x <= xmax:
+    for x in range(-xmax, xmax + 1):
         yD = b * b * x * x - 4 * c * (a * x * x - bound)
         if yD > 0:
             sqrt_yD = sqrt(yD)
             ymin = <long>ceil((-b * x - sqrt_yD) / (2 * c))
             ymax = <long>floor((-b * x + sqrt_yD) / (2 * c))
-            for y from ymin <= y <= ymax:
+            for y in range(ymin, ymax + 1):
                 terms[a * x * x + b * x * y + c * y * y] += 1
     sig_off()
     return terms
@@ -161,7 +161,7 @@ def gross_zagier_L_series(an_list, Q, long N, long u, var=None):
         i += 1
     sig_on()
     memcpy(terms, con_terms, sizeof(long) * bound)  # m = 1
-    for m from 2 <= m <= <long>sqrt(bound):
+    for m in range(2, <long>sqrt(bound) + 1):
         if arith.c_gcd_longlong(D * N, m) == 1:
             me = m * kronecker_symbol(D, m)
             j = 0

src/sage/modular/modsym/apply.pyx

@@ -103,7 +103,7 @@ def apply_to_monomial(int i, int j, int a, int b, int c, int d):
 
     cdef Integer res
     v = []
-    for k from 0 <= k <= j:
+    for k in range(j + 1):
         res = <Integer>PY_NEW(Integer)
         fmpz_poly_get_coeff_mpz(res.value, pr, k)
         v.append(int(res))

src/sage/modular/modsym/p1list.pyx

@@ -108,7 +108,7 @@ cdef int c_p1_normalize_int(int N, int u, int v,
         Ng = N/g
         vNg = (v*Ng) % N
         t = 1
-        for k from 2 <= k <= g:
+        for k in range(2, g + 1):
             v = (v + vNg) % N
             t = (t + Ng) % N
             if v<min_v and arith_int.c_gcd_int(t,N)==1:
@@ -220,8 +220,8 @@ def p1list_int(int N):
 
     lst = [(0,1)]
     c = 1
-    for d from 0 <= d < N:
-        lst.append((c,d))
+    for d in range(N):
+        lst.append((c, d))
 
     cmax = N // 2
     if N % 2:   # N odd, max divisor is <= N/3
@@ -230,11 +230,11 @@ def p1list_int(int N):
         else:
             cmax = N // 3
 
-    for c from 2 <= c <= cmax:
+    for c in range(2, cmax + 1):
         if N % c == 0:  # c is a proper divisor
             h = N // c
             g = arith_int.c_gcd_int(c, h)
-            for d from 1 <= d <= h:
+            for d in range(1, h + 1):
                 sig_check()
                 if arith_int.c_gcd_int(d, g) == 1:
                     d1 = d
@@ -373,10 +373,10 @@ cdef int c_p1_normalize_llong(int N, int u, int v,
         Ng = N/g
         vNg = <int> ((<llong>v * <llong> Ng) % ll_N)
         t = 1
-        for k from 2 <= k <= g:
+        for k in range(2, g + 1):
             v = (v + vNg) % N
             t = (t + Ng) % N
-            if v<min_v and arith_int.c_gcd_int(t,N)==1:
+            if v < min_v and arith_int.c_gcd_int(t, N) == 1:
                 min_v = v
                 min_t = t
     v = min_v
@@ -472,8 +472,8 @@ def p1list_llong(int N):
 
     lst = [(0,1)]
     c = 1
-    for d from 0 <= d < N:
-        lst.append((c,d))
+    for d in range(N):
+        lst.append((c, d))
 
     cmax = N // 2
     if N % 2:   # N odd, max divisor is <= N/3
@@ -482,18 +482,18 @@ def p1list_llong(int N):
         else:
             cmax = N // 3
 
-    for c from 2 <= c <= cmax:
+    for c in range(2, cmax + 1):
         if N % c == 0:  # c is a proper divisor
             h = N // c
             g = arith_int.c_gcd_int(c, h)
-            for d from 1 <= d <= h:
+            for d in range(1, h + 1):
                 if arith_int.c_gcd_int(d, g) == 1:
                     sig_check()
                     d1 = d
                     while arith_int.c_gcd_int(d1, c) != 1:
                         d1 += h
                     c_p1_normalize_llong(N, c, d1, &u, &v, &s, 0)
-                    lst.append((u,v))
+                    lst.append((u, v))
     lst.sort()
     return lst
 
@@ -663,7 +663,7 @@ cdef int p1_normalize_xgcdtable(int N, int u, int v,
         Ng = N/g
         vNg = (v*Ng) % N
         t = 1
-        for k from 2 <= k <= g:
+        for k in range(2, g + 1):
             v = (v + vNg) % N
             t = (t + Ng) % N
             if v < min_v and t_g[t] == 1:     # arith_int.c_gcd_int(t,N)==1:
@@ -744,10 +744,10 @@ cdef class P1List():
         cdef llong ll_s, ll_t, ll_N = N
 
         if N <= 46340:
-            for i from 0 <= i < N:
+            for i in range(N):
                 self.g[i] = arith_int.c_xgcd_int(i, N, &self.s[i], &self.t[i])
         else:
-            for i from 0 <= i < N:
+            for i in range(N):
                 self.g[i] = arith_llong.c_xgcd_longlong(i, N, &ll_s, &ll_t)
                 self.s[i] = <int>(ll_s % ll_N)
                 self.t[i] = <int>(ll_t % ll_N)