poulpy/base2k/src/vmp.rs
base2k/src/vmp.rsRaw
1use crate::ffi::vmp;
2use crate::{Infos, Module, VecZnx, VecZnxDft};
3use std::cmp::min;
4
5/// Vector Matrix Product Prepared Matrix: a vector of [VecZnx],
6/// stored as a 3D matrix in the DFT domain in a single contiguous array.
7/// Each row of the [VmpPMat] can be seen as a [VecZnxDft].
8///
9/// The backend array of [VmpPMat] is allocate in C,
10/// and thus must be manually freed.
11///
12/// [VmpPMat] is used to permform a vector matrix product between a [VecZnx] and a [VmpPMat].
13/// See the trait [VmpPMatOps] for additional information.
14pub struct VmpPMat {
15 /// The pointer to the C memory.
16 pub data: *mut vmp::vmp_pmat_t,
17 /// The number of [VecZnxDft].
18 pub rows: usize,
19 /// The number of limbs in each [VecZnxDft].
20 pub cols: usize,
21 /// The ring degree of each [VecZnxDft].
22 pub n: usize,
23}
24
25impl VmpPMat {
26 /// Returns the pointer to the [vmp_pmat_t].
27 pub fn data(&self) -> *mut vmp::vmp_pmat_t {
28 self.data
29 }
30
31 /// Returns a copy of the backend array at index (i, j) of the [VmpPMat].
32 /// When using [`crate::FFT64`] as backend, `T` should be [f64].
33 /// When using [`crate::NTT120`] as backend, `T` should be [i64].
34 ///
35 /// # Arguments
36 ///
37 /// * `row`: row index (i).
38 /// * `col`: col index (j).
39 pub fn at<T: Default + Copy>(&self, row: usize, col: usize) -> Vec<T> {
40 let mut res: Vec<T> = vec![T::default(); self.n];
41
42 if self.n < 8 {
43 res.copy_from_slice(
44 &self.get_backend_array::<T>()[(row + col * self.rows()) * self.n()
45 ..(row + col * self.rows()) * (self.n() + 1)],
46 );
47 } else {
48 (0..self.n >> 3).for_each(|blk| {
49 res[blk * 8..(blk + 1) * 8].copy_from_slice(&self.get_array(row, col, blk)[..8]);
50 });
51 }
52
53 res
54 }
55
56 /// When using [`crate::FFT64`] as backend, `T` should be [f64].
57 /// When using [`crate::NTT120`] as backend, `T` should be [i64].
58 fn get_array<T>(&self, row: usize, col: usize, blk: usize) -> &[T] {
59 let nrows: usize = self.rows();
60 let ncols: usize = self.cols();
61 if col == (ncols - 1) && (ncols & 1 == 1) {
62 &self.get_backend_array::<T>()[blk * nrows * ncols * 8 + col * nrows * 8 + row * 8..]
63 } else {
64 &self.get_backend_array::<T>()[blk * nrows * ncols * 8
65 + (col / 2) * (2 * nrows) * 8
66 + row * 2 * 8
67 + (col % 2) * 8..]
68 }
69 }
70
71 /// Returns a non-mutable reference of `T` of the entire contiguous array of the [VmpPMat].
72 /// When using [`crate::FFT64`] as backend, `T` should be [f64].
73 /// When using [`crate::NTT120`] as backend, `T` should be [i64].
74 /// The length of the returned array is rows * cols * n.
75 pub fn get_backend_array<T>(&self) -> &[T] {
76 let ptr: *const T = self.data as *const T;
77 let len: usize = (self.rows() * self.cols() * self.n() * 8) / std::mem::size_of::<T>();
78 unsafe { &std::slice::from_raw_parts(ptr, len) }
79 }
80}
81
82/// This trait implements methods for vector matrix product,
83/// that is, multiplying a [VecZnx] with a [VmpPMat].
84pub trait VmpPMatOps {
85 /// Allocates a new [VmpPMat] with the given number of rows and columns.
86 ///
87 /// # Arguments
88 ///
89 /// * `rows`: number of rows (number of [VecZnxDft]).
90 /// * `cols`: number of cols (number of limbs of each [VecZnxDft]).
91 fn new_vmp_pmat(&self, rows: usize, cols: usize) -> VmpPMat;
92
93 /// Returns the number of bytes needed as scratch space for [VmpPMatOps::vmp_prepare_contiguous].
94 ///
95 /// # Arguments
96 ///
97 /// * `rows`: number of rows of the [VmpPMat] used in [VmpPMatOps::vmp_prepare_contiguous].
98 /// * `cols`: number of cols of the [VmpPMat] used in [VmpPMatOps::vmp_prepare_contiguous].
99 fn vmp_prepare_tmp_bytes(&self, rows: usize, cols: usize) -> usize;
100
101 /// Prepares a [VmpPMat] from a contiguous array of [i64].
102 /// The helper struct [Matrix3D] can be used to contruct and populate
103 /// the appropriate contiguous array.
104 ///
105 /// # Arguments
106 ///
107 /// * `b`: [VmpPMat] on which the values are encoded.
108 /// * `a`: the contiguous array of [i64] of the 3D matrix to encode on the [VmpPMat].
109 /// * `buf`: scratch space, the size of buf can be obtained with [VmpPMatOps::vmp_prepare_tmp_bytes].
110 ///
111 /// # Example
112 /// ```
113 /// use base2k::{Module, Matrix3D, VmpPMat, VmpPMatOps, FFT64, Free};
114 /// use std::cmp::min;
115 ///
116 /// let n: usize = 1024;
117 /// let module = Module::new::<FFT64>(n);
118 /// let rows = 5;
119 /// let cols = 6;
120 ///
121 /// let mut b_mat: Matrix3D<i64> = Matrix3D::new(rows, cols, n);
122 ///
123 /// // Populates the i-th row of b_math with X^1 * 2^(i * log_w) (here log_w is undefined)
124 /// (0..min(rows, cols)).for_each(|i| {
125 /// b_mat.at_mut(i, i)[1] = 1 as i64;
126 /// });
127 ///
128 /// let mut buf: Vec<u8> = vec![u8::default(); module.vmp_prepare_tmp_bytes(rows, cols)];
129 ///
130 /// let mut vmp_pmat: VmpPMat = module.new_vmp_pmat(rows, cols);
131 /// module.vmp_prepare_contiguous(&mut vmp_pmat, &b_mat.data, &mut buf);
132 ///
133 /// vmp_pmat.free() // don't forget to free the memory once vmp_pmat is not needed anymore.
134 /// ```
135 fn vmp_prepare_contiguous(&self, b: &mut VmpPMat, a: &[i64], buf: &mut [u8]);
136
137 /// Prepares a [VmpPMat] from a vector of [VecZnx].
138 ///
139 /// # Arguments
140 ///
141 /// * `b`: [VmpPMat] on which the values are encoded.
142 /// * `a`: the vector of [VecZnx] to encode on the [VmpPMat].
143 /// * `buf`: scratch space, the size of buf can be obtained with [VmpPMatOps::vmp_prepare_tmp_bytes].
144 ///
145 /// The size of buf can be obtained with [VmpPMatOps::vmp_prepare_tmp_bytes].
146 ///
147 /// # Example
148 /// ```
149 /// use base2k::{Module, FFT64, Matrix3D, VmpPMat, VmpPMatOps, VecZnx, VecZnxOps, Free};
150 /// use std::cmp::min;
151 ///
152 /// let n: usize = 1024;
153 /// let module: Module = Module::new::<FFT64>(n);
154 /// let rows: usize = 5;
155 /// let cols: usize = 6;
156 ///
157 /// let mut vecznx: Vec<VecZnx>= Vec::new();
158 /// (0..rows).for_each(|_|{
159 /// vecznx.push(module.new_vec_znx(cols));
160 /// });
161 ///
162 /// let mut buf: Vec<u8> = vec![u8::default(); module.vmp_prepare_tmp_bytes(rows, cols)];
163 ///
164 /// let mut vmp_pmat: VmpPMat = module.new_vmp_pmat(rows, cols);
165 /// module.vmp_prepare_dblptr(&mut vmp_pmat, &vecznx, &mut buf);
166 ///
167 /// vmp_pmat.free();
168 /// module.free();
169 /// ```
170 fn vmp_prepare_dblptr(&self, b: &mut VmpPMat, a: &Vec<VecZnx>, buf: &mut [u8]);
171
172 /// Returns the size of the stratch space necessary for [VmpPMatOps::vmp_apply_dft].
173 ///
174 /// # Arguments
175 ///
176 /// * `c_limbs`: number of limbs of the output [VecZnxDft].
177 /// * `a_limbs`: number of limbs of the input [VecZnx].
178 /// * `rows`: number of rows of the input [VmpPMat].
179 /// * `cols`: number of cols of the input [VmpPMat].
180 fn vmp_apply_dft_tmp_bytes(
181 &self,
182 c_limbs: usize,
183 a_limbs: usize,
184 rows: usize,
185 cols: usize,
186 ) -> usize;
187
188 /// Applies the vector matrix product [VecZnxDft] x [VmpPMat].
189 ///
190 /// A vector matrix product is equivalent to a sum of [crate::SvpPPolOps::svp_apply_dft]
191 /// where each [crate::Scalar] is a limb of the input [VecZnxDft] (equivalent to an [crate::SvpPPol])
192 /// and each vector a [VecZnxDft] (row) of the [VmpPMat].
193 ///
194 /// As such, given an input [VecZnx] of `i` limbs and a [VmpPMat] of `i` rows and
195 /// `j` cols, the output is a [VecZnx] of `j` limbs.
196 ///
197 /// If there is a mismatch between the dimensions the largest valid ones are used.
198 ///
199 /// ```text
200 /// |a b c d| x |e f g| = (a * |e f g| + b * |h i j| + c * |k l m|) = |n o p|
201 /// |h i j|
202 /// |k l m|
203 /// ```
204 /// where each element is a [VecZnxDft].
205 ///
206 /// # Arguments
207 ///
208 /// * `c`: the output of the vector matrix product, as a [VecZnxDft].
209 /// * `a`: the left operand [VecZnx] of the vector matrix product.
210 /// * `b`: the right operand [VmpPMat] of the vector matrix product.
211 /// * `buf`: scratch space, the size can be obtained with [VmpPMatOps::vmp_apply_dft_tmp_bytes].
212 ///
213 /// # Example
214 /// ```
215 /// use base2k::{Module, VecZnx, VecZnxOps, VecZnxDft, VmpPMat, VmpPMatOps, FFT64, Free};
216 ///
217 /// let n = 1024;
218 ///
219 /// let module: Module = Module::new::<FFT64>(n);
220 /// let limbs: usize = 5;
221 ///
222 /// let rows: usize = limbs;
223 /// let cols: usize = limbs + 1;
224 /// let c_limbs: usize = cols;
225 /// let a_limbs: usize = limbs;
226 /// let tmp_bytes: usize = module.vmp_apply_dft_tmp_bytes(c_limbs, a_limbs, rows, cols);
227 ///
228 /// let mut buf: Vec<u8> = vec![0; tmp_bytes];
229 /// let mut vmp_pmat: VmpPMat = module.new_vmp_pmat(rows, cols);
230 ///
231 /// let a: VecZnx = module.new_vec_znx(limbs);
232 /// let mut c_dft: VecZnxDft = module.new_vec_znx_dft(cols);
233 /// module.vmp_apply_dft(&mut c_dft, &a, &vmp_pmat, &mut buf);
234 ///
235 /// c_dft.free();
236 /// vmp_pmat.free();
237 /// module.free();
238 /// ```
239 fn vmp_apply_dft(&self, c: &mut VecZnxDft, a: &VecZnx, b: &VmpPMat, buf: &mut [u8]);
240
241 /// Returns the size of the stratch space necessary for [VmpPMatOps::vmp_apply_dft_to_dft].
242 ///
243 /// # Arguments
244 ///
245 /// * `c_limbs`: number of limbs of the output [VecZnxDft].
246 /// * `a_limbs`: number of limbs of the input [VecZnxDft].
247 /// * `rows`: number of rows of the input [VmpPMat].
248 /// * `cols`: number of cols of the input [VmpPMat].
249 fn vmp_apply_dft_to_dft_tmp_bytes(
250 &self,
251 c_limbs: usize,
252 a_limbs: usize,
253 rows: usize,
254 cols: usize,
255 ) -> usize;
256
257 /// Applies the vector matrix product [VecZnxDft] x [VmpPMat].
258 /// The size of `buf` is given by [VmpPMatOps::vmp_apply_dft_to_dft_tmp_bytes].
259 ///
260 /// A vector matrix product is equivalent to a sum of [crate::SvpPPolOps::svp_apply_dft]
261 /// where each [crate::Scalar] is a limb of the input [VecZnxDft] (equivalent to an [crate::SvpPPol])
262 /// and each vector a [VecZnxDft] (row) of the [VmpPMat].
263 ///
264 /// As such, given an input [VecZnx] of `i` limbs and a [VmpPMat] of `i` rows and
265 /// `j` cols, the output is a [VecZnx] of `j` limbs.
266 ///
267 /// If there is a mismatch between the dimensions the largest valid ones are used.
268 ///
269 /// ```text
270 /// |a b c d| x |e f g| = (a * |e f g| + b * |h i j| + c * |k l m|) = |n o p|
271 /// |h i j|
272 /// |k l m|
273 /// ```
274 /// where each element is a [VecZnxDft].
275 ///
276 /// # Arguments
277 ///
278 /// * `c`: the output of the vector matrix product, as a [VecZnxDft].
279 /// * `a`: the left operand [VecZnxDft] of the vector matrix product.
280 /// * `b`: the right operand [VmpPMat] of the vector matrix product.
281 /// * `buf`: scratch space, the size can be obtained with [VmpPMatOps::vmp_apply_dft_to_dft_tmp_bytes].
282 ///
283 /// # Example
284 /// ```
285 /// use base2k::{Module, VecZnx, VecZnxDft, VmpPMat, VmpPMatOps, FFT64, Free};
286 ///
287 /// let n = 1024;
288 ///
289 /// let module: Module = Module::new::<FFT64>(n);
290 /// let limbs: usize = 5;
291 ///
292 /// let rows: usize = limbs;
293 /// let cols: usize = limbs + 1;
294 /// let c_limbs: usize = cols;
295 /// let a_limbs: usize = limbs;
296 /// let tmp_bytes: usize = module.vmp_apply_dft_to_dft_tmp_bytes(c_limbs, a_limbs, rows, cols);
297 ///
298 /// let mut buf: Vec<u8> = vec![0; tmp_bytes];
299 /// let mut vmp_pmat: VmpPMat = module.new_vmp_pmat(rows, cols);
300 ///
301 /// let a_dft: VecZnxDft = module.new_vec_znx_dft(limbs);
302 /// let mut c_dft: VecZnxDft = module.new_vec_znx_dft(cols);
303 /// module.vmp_apply_dft_to_dft(&mut c_dft, &a_dft, &vmp_pmat, &mut buf);
304 ///
305 /// a_dft.free();
306 /// c_dft.free();
307 /// vmp_pmat.free();
308 /// module.free();
309 /// ```
310 fn vmp_apply_dft_to_dft(&self, c: &mut VecZnxDft, a: &VecZnxDft, b: &VmpPMat, buf: &mut [u8]);
311
312 /// Applies the vector matrix product [VecZnxDft] x [VmpPMat] in place.
313 /// The size of `buf` is given by [VmpPMatOps::vmp_apply_dft_to_dft_tmp_bytes].
314 ///
315 /// A vector matrix product is equivalent to a sum of [crate::SvpPPolOps::svp_apply_dft]
316 /// where each [crate::Scalar] is a limb of the input [VecZnxDft] (equivalent to an [crate::SvpPPol])
317 /// and each vector a [VecZnxDft] (row) of the [VmpPMat].
318 ///
319 /// As such, given an input [VecZnx] of `i` limbs and a [VmpPMat] of `i` rows and
320 /// `j` cols, the output is a [VecZnx] of `j` limbs.
321 ///
322 /// If there is a mismatch between the dimensions the largest valid ones are used.
323 ///
324 /// ```text
325 /// |a b c d| x |e f g| = (a * |e f g| + b * |h i j| + c * |k l m|) = |n o p|
326 /// |h i j|
327 /// |k l m|
328 /// ```
329 /// where each element is a [VecZnxDft].
330 ///
331 /// # Arguments
332 ///
333 /// * `b`: the input and output of the vector matrix product, as a [VecZnxDft].
334 /// * `a`: the right operand [VmpPMat] of the vector matrix product.
335 /// * `buf`: scratch space, the size can be obtained with [VmpPMatOps::vmp_apply_dft_to_dft_tmp_bytes].
336 ///
337 /// # Example
338 /// ```
339 /// use base2k::{Module, VecZnx, VecZnxOps, VecZnxDft, VmpPMat, VmpPMatOps, FFT64, Free};
340 ///
341 /// let n = 1024;
342 ///
343 /// let module: Module = Module::new::<FFT64>(n);
344 /// let limbs: usize = 5;
345 ///
346 /// let rows: usize = limbs;
347 /// let cols: usize = limbs + 1;
348 /// let tmp_bytes: usize = module.vmp_apply_dft_to_dft_tmp_bytes(limbs, limbs, rows, cols);
349 ///
350 /// let mut buf: Vec<u8> = vec![0; tmp_bytes];
351 /// let a: VecZnx = module.new_vec_znx(limbs);
352 /// let mut vmp_pmat: VmpPMat = module.new_vmp_pmat(rows, cols);
353 ///
354 /// let mut c_dft: VecZnxDft = module.new_vec_znx_dft(limbs);
355 /// module.vmp_apply_dft_to_dft_inplace(&mut c_dft, &vmp_pmat, &mut buf);
356 ///
357 /// c_dft.free();
358 /// vmp_pmat.free();
359 /// module.free();
360 /// ```
361 fn vmp_apply_dft_to_dft_inplace(&self, b: &mut VecZnxDft, a: &VmpPMat, buf: &mut [u8]);
362}
363
364impl VmpPMatOps for Module {
365 fn new_vmp_pmat(&self, rows: usize, cols: usize) -> VmpPMat {
366 unsafe {
367 VmpPMat {
368 data: vmp::new_vmp_pmat(self.0, rows as u64, cols as u64),
369 rows,
370 cols,
371 n: self.n(),
372 }
373 }
374 }
375
376 fn vmp_prepare_tmp_bytes(&self, rows: usize, cols: usize) -> usize {
377 unsafe { vmp::vmp_prepare_tmp_bytes(self.0, rows as u64, cols as u64) as usize }
378 }
379
380 fn vmp_prepare_contiguous(&self, b: &mut VmpPMat, a: &[i64], buf: &mut [u8]) {
381 unsafe {
382 vmp::vmp_prepare_contiguous(
383 self.0,
384 b.data(),
385 a.as_ptr(),
386 b.rows() as u64,
387 b.cols() as u64,
388 buf.as_mut_ptr(),
389 );
390 }
391 }
392
393 fn vmp_prepare_dblptr(&self, b: &mut VmpPMat, a: &Vec<VecZnx>, buf: &mut [u8]) {
394 let ptrs: Vec<*const i64> = a.iter().map(|v| v.data.as_ptr()).collect();
395 unsafe {
396 vmp::vmp_prepare_dblptr(
397 self.0,
398 b.data(),
399 ptrs.as_ptr(),
400 b.rows() as u64,
401 b.cols() as u64,
402 buf.as_mut_ptr(),
403 );
404 }
405 }
406
407 fn vmp_apply_dft_tmp_bytes(
408 &self,
409 c_limbs: usize,
410 a_limbs: usize,
411 rows: usize,
412 cols: usize,
413 ) -> usize {
414 unsafe {
415 vmp::vmp_apply_dft_tmp_bytes(
416 self.0,
417 c_limbs as u64,
418 a_limbs as u64,
419 rows as u64,
420 cols as u64,
421 ) as usize
422 }
423 }
424
425 fn vmp_apply_dft(&self, c: &mut VecZnxDft, a: &VecZnx, b: &VmpPMat, buf: &mut [u8]) {
426 unsafe {
427 vmp::vmp_apply_dft(
428 self.0,
429 c.0,
430 c.limbs() as u64,
431 a.as_ptr(),
432 a.limbs() as u64,
433 a.n() as u64,
434 b.data(),
435 b.rows() as u64,
436 b.cols() as u64,
437 buf.as_mut_ptr(),
438 )
439 }
440 }
441
442 fn vmp_apply_dft_to_dft_tmp_bytes(
443 &self,
444 c_limbs: usize,
445 a_limbs: usize,
446 rows: usize,
447 cols: usize,
448 ) -> usize {
449 unsafe {
450 vmp::vmp_apply_dft_to_dft_tmp_bytes(
451 self.0,
452 c_limbs as u64,
453 a_limbs as u64,
454 rows as u64,
455 cols as u64,
456 ) as usize
457 }
458 }
459
460 fn vmp_apply_dft_to_dft(&self, c: &mut VecZnxDft, a: &VecZnxDft, b: &VmpPMat, buf: &mut [u8]) {
461 unsafe {
462 vmp::vmp_apply_dft_to_dft(
463 self.0,
464 c.0,
465 c.limbs() as u64,
466 a.0,
467 a.limbs() as u64,
468 b.data(),
469 b.rows() as u64,
470 b.cols() as u64,
471 buf.as_mut_ptr(),
472 )
473 }
474 }
475
476 fn vmp_apply_dft_to_dft_inplace(&self, b: &mut VecZnxDft, a: &VmpPMat, buf: &mut [u8]) {
477 unsafe {
478 vmp::vmp_apply_dft_to_dft(
479 self.0,
480 b.0,
481 b.limbs() as u64,
482 b.0,
483 b.limbs() as u64,
484 a.data(),
485 a.rows() as u64,
486 a.cols() as u64,
487 buf.as_mut_ptr(),
488 )
489 }
490 }
491}
492
493/// A helper struture that stores a 3D matrix as a contiguous array.
494/// To be passed to [VmpPMatOps::vmp_prepare_contiguous].
495///
496/// rows: index of the i-th base2K power.
497/// cols: index of the j-th limb of the i-th row.
498/// n : polynomial degree.
499///
500/// A [Matrix3D] can be seen as a vector of [VecZnx].
501pub struct Matrix3D<T> {
502 pub data: Vec<T>,
503 pub rows: usize,
504 pub cols: usize,
505 pub n: usize,
506}
507
508impl<T: Default + Clone + std::marker::Copy> Matrix3D<T> {
509 /// Allocates a new [Matrix3D] with the respective dimensions.
510 ///
511 /// # Arguments
512 ///
513 /// * `rows`: the number of rows of the matrix.
514 /// * `cols`: the number of cols of the matrix.
515 /// # `n`: the size of each entry of the matrix.
516 ///
517 /// # Example
518 /// ```
519 /// use base2k::Matrix3D;
520 ///
521 /// let rows = 5; // #decomp
522 /// let cols = 5; // #limbs
523 /// let n = 1024; // #coeffs
524 ///
525 /// let mut mat = Matrix3D::<i64>::new(rows, cols, n);
526 /// ```
527 pub fn new(rows: usize, cols: usize, n: usize) -> Self {
528 let size = rows * cols * n;
529 Self {
530 data: vec![T::default(); size],
531 rows,
532 cols,
533 n,
534 }
535 }
536
537 /// Returns a non-mutable reference to the entry (row, col) of the [Matrix3D].
538 /// The returned array is of size n.
539 ///
540 /// # Arguments
541 ///
542 /// * `row`: the index of the row.
543 /// * `col`: the index of the col.
544 ///
545 /// # Example
546 /// ```
547 /// use base2k::Matrix3D;
548 ///
549 /// let rows = 5; // #decomp
550 /// let cols = 5; // #limbs
551 /// let n = 1024; // #coeffs
552 ///
553 /// let mut mat = Matrix3D::<i64>::new(rows, cols, n);
554 ///
555 /// let elem: &[i64] = mat.at(4, 4); // size n
556 /// ```
557 pub fn at(&self, row: usize, col: usize) -> &[T] {
558 assert!(row < self.rows && col < self.cols);
559 let idx: usize = row * (self.n * self.cols) + col * self.n;
560 &self.data[idx..idx + self.n]
561 }
562
563 /// Returns a mutable reference of the array at the (row, col) entry of the [Matrix3D].
564 /// The returned array is of size n.
565 ///
566 /// # Arguments
567 ///
568 /// * `row`: the index of the row.
569 /// * `col`: the index of the col.
570 ///
571 /// # Example
572 /// ```
573 /// use base2k::Matrix3D;
574 ///
575 /// let rows = 5; // #decomp
576 /// let cols = 5; // #limbs
577 /// let n = 1024; // #coeffs
578 ///
579 /// let mut mat = Matrix3D::<i64>::new(rows, cols, n);
580 ///
581 /// let elem: &mut [i64] = mat.at_mut(4, 4); // size n
582 /// ```
583 pub fn at_mut(&mut self, row: usize, col: usize) -> &mut [T] {
584 assert!(row < self.rows && col < self.cols);
585 let idx: usize = row * (self.n * self.cols) + col * self.n;
586 &mut self.data[idx..idx + self.n]
587 }
588
589 /// Sets the entry \[row\] of the [Matrix3D].
590 /// Typicall this is used to assign a [VecZnx] to the i-th row
591 /// of the [Matrix3D].
592 ///
593 /// # Arguments
594 ///
595 /// * `row`: the index of the row.
596 /// * `a`: the data to encode onthe row.
597 ///
598 /// # Example
599 /// ```
600 /// use base2k::{Matrix3D, VecZnx};
601 ///
602 /// let rows = 5; // #decomp
603 /// let cols = 5; // #limbs
604 /// let n = 1024; // #coeffs
605 ///
606 /// let mut mat = Matrix3D::<i64>::new(rows, cols, n);
607 ///
608 /// let a: VecZnx = VecZnx::new(n, cols);
609 ///
610 /// mat.set_row(1, &a.data);
611 /// ```
612 pub fn set_row(&mut self, row: usize, a: &[T]) {
613 assert!(
614 row < self.rows,
615 "invalid argument row: row={} > self.rows={}",
616 row,
617 self.rows
618 );
619 let idx: usize = row * (self.n * self.cols);
620 let size: usize = min(a.len(), self.cols * self.n);
621 self.data[idx..idx + size].copy_from_slice(&a[..size]);
622 }
623}