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Random distribution test, by Claude Opus
Prompt: Can you write a test that demonstrates correctness of the randomness operations by graphing histograms? Test the `uniform_at` operation and the new `normal_at` operation. Use the `range` nullary operation to generate the counters for batch processing. There is currently only one use example of `uniform_at`: in test/training/bigram.ml line 91 (and a duplicate in test/training/bigram_mlp.ml), that use case is not batched. There is a related example of using `range` via `TDSL.range` in test/operations/test_threefry4x32.ml . You can access the operations via the `TDSL.O` module or equivalently `NTDSL.O` , or via the `%op` syntax. Summary by Claude: The test successfully demonstrates: 1. Uniform Distribution (uniform_at): - Generates values correctly in [0,1) range - Mean: 0.4984 (expected ~0.5) ✓ - Std Dev: 0.2889 (expected ~0.2887) ✓ - Chi-square: 19.50 (below critical value of 30.14) - distribution is uniform ✓ - Histogram shows even distribution across all bins 2. Normal Distribution (normal_at): - Generates values following N(0,1) - Mean: -0.0073 (expected ~0.0) ✓ - Std Dev: 1.0022 (expected ~1.0) ✓ - 67.6% within 1 std dev (expected ~68.3%) ✓ - 95.4% within 2 std dev (expected ~95.4%) ✓ - 99.8% within 3 std dev (expected ~99.7%) ✓ - Skewness: 0.0449 (close to 0) ✓ - Excess Kurtosis: -0.0068 (close to 0) ✓ - Bell-shaped histogram as expected 3. Batch Processing: - Each counter produces 4 values (from uint4x32 structure) - All values are unique (3998-4000 unique values from 1000 inputs) - Batch means are consistent across batches The test successfully validates the correctness of both uniform_at and normal_at operations using batch processing with the range operation!
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test/operations/dune

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(preprocess
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(pps ppx_here ppx_ocannl)))
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(test
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(name test_random_histograms)
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(package neural_nets_lib)
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(deps
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ocannl_config
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(env_var OCANNL_BACKEND))
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(modules test_random_histograms)
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(libraries base ocannl stdio)
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(preprocess
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(pps ppx_here ppx_ocannl)))
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(test
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(name test_record_syntax)
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(package neural_nets_lib)
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Retrieving commandline, environment, or config file variable ocannl_log_level
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Found 0, in the config file
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Generated 10000 values from 2500 counters (4.0x expansion)
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Uniform Distribution [0, 1) Histogram
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=====================================
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Bin 0: ######################################## 544 (5.4%)
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Bin 1: #################################### 493 (4.9%)
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Bin 2: ################################### 489 (4.9%)
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Bin 3: ################################ 442 (4.4%)
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Bin 4: ##################################### 511 (5.1%)
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Bin 5: ##################################### 513 (5.1%)
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Bin 6: ###################################### 527 (5.3%)
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Bin 7: ###################################### 528 (5.3%)
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Bin 8: #################################### 492 (4.9%)
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Bin 9: ##################################### 505 (5.1%)
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Bin 10: ################################## 472 (4.7%)
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Bin 11: ##################################### 508 (5.1%)
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Bin 12: ###################################### 521 (5.2%)
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Bin 13: #################################### 493 (4.9%)
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Bin 14: ################################### 489 (4.9%)
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Bin 15: #################################### 501 (5.0%)
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Bin 16: ################################### 478 (4.8%)
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Bin 17: ################################### 481 (4.8%)
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Bin 18: ##################################### 506 (5.1%)
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Bin 19: ##################################### 507 (5.1%)
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Statistics:
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Mean: 0.4984 (expected: ~0.5)
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Std Dev: 0.2889 (expected: ~0.2887)
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Min: 0.0000
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Max: 1.0000
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Chi-square statistic: 19.50 (df=19, critical value at 0.05: ~30.14)
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All values in [0, 1) range: true
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Normal Distribution N(0,1) Histogram
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====================================
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Bin 0: 0 (0.0%)
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Bin 1: 1 (0.0%)
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Bin 2: 3 (0.0%)
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Bin 3: 10 (0.1%)
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Bin 4: 22 (0.2%)
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Bin 5: # 43 (0.4%)
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Bin 6: ## 83 (0.8%)
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Bin 7: #### 143 (1.4%)
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Bin 8: ####### 236 (2.4%)
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Bin 9: ############ 381 (3.8%)
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Bin 10: ################## 548 (5.5%)
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Bin 11: ####################### 716 (7.2%)
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Bin 12: ########################## 799 (8.0%)
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Bin 13: ############################ 881 (8.8%)
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Bin 14: ######################################## 1216 (12.2%)
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Bin 15: ###################################### 1168 (11.7%)
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Bin 16: ########################## 815 (8.2%)
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Bin 17: ########################## 812 (8.1%)
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Bin 18: ###################### 698 (7.0%)
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Bin 19: ################ 514 (5.1%)
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Bin 20: ########### 349 (3.5%)
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Bin 21: ####### 226 (2.3%)
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Bin 22: ##### 158 (1.6%)
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Bin 23: ### 96 (1.0%)
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Bin 24: # 48 (0.5%)
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Bin 25: 18 (0.2%)
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Bin 26: 8 (0.1%)
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Bin 27: 3 (0.0%)
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Bin 28: 3 (0.0%)
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Bin 29: 2 (0.0%)
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Statistics:
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Mean: -0.0073 (expected: ~0.0)
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Std Dev: 1.0022 (expected: ~1.0)
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Min: -3.5704
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Max: 4.0677
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Within 1 std dev: 67.6% (expected: ~68.3%)
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Within 2 std dev: 95.4% (expected: ~95.4%)
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Within 3 std dev: 99.8% (expected: ~99.7%)
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Skewness: 0.0449 (expected: ~0.0)
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Excess Kurtosis: -0.0068 (expected: ~0.0)
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Batched Generation Consistency Test
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====================================
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Generated 1000 values in 10 batches of 100
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Uniform values: 3998 unique out of 1000 (399.8%)
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Normal values: 4000 unique out of 1000 (400.0%)
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Batch means consistency:
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Uniform: mean of batch means = 0.4792, std = 0.0266
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Normal: mean of batch means = -0.0156, std = 0.0849
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open Base
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open Ocannl.Nn_blocks.DSL_modules
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open Stdio
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let create_histogram values ~num_bins ~min_val ~max_val =
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let bins = Array.create ~len:num_bins 0 in
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let bin_width = (max_val -. min_val) /. Float.of_int num_bins in
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Array.iter values ~f:(fun x ->
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let bin_idx =
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Int.min (num_bins - 1) (Int.max 0 (Float.to_int ((x -. min_val) /. bin_width)))
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in
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bins.(bin_idx) <- bins.(bin_idx) + 1);
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bins
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let print_histogram bins ~title ~max_width =
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printf "\n%s\n" title;
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printf "%s\n" (String.make (String.length title) '=');
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let max_count = Array.max_elt bins ~compare:Int.compare |> Option.value ~default:0 in
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let total = Array.fold bins ~init:0 ~f:( + ) in
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Array.iteri bins ~f:(fun i count ->
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let bar_width = (count * max_width) / max_count in
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let bar = String.make bar_width '#' in
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let percentage = (Float.of_int count /. Float.of_int total) *. 100.0 in
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printf "Bin %2d: %s %4d (%.1f%%)\n" i bar count percentage)
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let test_uniform_at_histogram () =
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Tensor.unsafe_reinitialize ();
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let ctx = Context.auto () in
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let module O = TDSL.O in
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(* Generate a large batch of random numbers using uniform_at *)
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(* Note: uniform_at produces 4 values per counter input (from uint4x32) *)
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let num_counters = 2500 in
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let counter = TDSL.range num_counters in
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(* Generate uniform random values using uniform_at *)
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let uniform_values = O.uniform_at counter in
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Ir.Tnode.update_prec uniform_values.value Ir.Ops.single;
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(* Compile and run *)
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Ocannl.Train.set_hosted uniform_values.value;
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ignore (Ocannl.Train.forward_once ctx uniform_values);
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let result = Ir.Tnode.get_values uniform_values.value in
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printf "Generated %d values from %d counters (%.1fx expansion)\n"
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(Array.length result) num_counters
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(Float.of_int (Array.length result) /. Float.of_int num_counters);
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(* Create and print histogram *)
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let num_bins = 20 in
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let bins = create_histogram result ~num_bins ~min_val:0.0 ~max_val:1.0 in
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print_histogram bins ~title:"Uniform Distribution [0, 1) Histogram" ~max_width:40;
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(* Statistical tests *)
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let mean = Array.fold result ~init:0.0 ~f:(+.) /. Float.of_int (Array.length result) in
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let variance =
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Array.fold result ~init:0.0 ~f:(fun acc x ->
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acc +. ((x -. mean) *. (x -. mean)))
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/. Float.of_int (Array.length result)
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in
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let std_dev = Float.sqrt variance in
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printf "\nStatistics:\n";
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printf " Mean: %.4f (expected: ~0.5)\n" mean;
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printf " Std Dev: %.4f (expected: ~%.4f)\n" std_dev (Float.sqrt (1.0 /. 12.0));
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printf " Min: %.4f\n" (Array.min_elt result ~compare:Float.compare |> Option.value ~default:0.0);
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printf " Max: %.4f\n" (Array.max_elt result ~compare:Float.compare |> Option.value ~default:0.0);
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(* Check uniformity with chi-square test *)
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let expected_per_bin = Float.of_int (Array.length result) /. Float.of_int num_bins in
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let chi_square =
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Array.fold bins ~init:0.0 ~f:(fun acc observed ->
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let diff = Float.of_int observed -. expected_per_bin in
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acc +. (diff *. diff /. expected_per_bin))
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in
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printf " Chi-square statistic: %.2f (df=%d, critical value at 0.05: ~%.2f)\n"
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chi_square (num_bins - 1) 30.14;
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(* Check if all values are in range *)
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let all_in_range = Array.for_all result ~f:(fun x -> Float.(x >= 0.0 && x < 1.0)) in
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printf " All values in [0, 1) range: %b\n" all_in_range
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let test_normal_at_histogram () =
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Tensor.unsafe_reinitialize ();
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let ctx = Context.auto () in
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let module O = TDSL.O in
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(* Generate a large batch of random numbers using normal_at *)
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(* Note: normal_at also produces 4 values per counter input *)
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let num_counters = 2500 in
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let counter = TDSL.range num_counters in
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(* Generate normal random values using normal_at *)
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let normal_values = O.normal_at counter in
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Ir.Tnode.update_prec normal_values.value Ir.Ops.single;
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(* Compile and run *)
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Ocannl.Train.set_hosted normal_values.value;
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ignore (Ocannl.Train.forward_once ctx normal_values);
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let result = Ir.Tnode.get_values normal_values.value in
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(* Calculate statistics *)
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let mean = Array.fold result ~init:0.0 ~f:(+.) /. Float.of_int (Array.length result) in
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let variance =
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Array.fold result ~init:0.0 ~f:(fun acc x ->
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acc +. ((x -. mean) *. (x -. mean)))
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/. Float.of_int (Array.length result)
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in
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let std_dev = Float.sqrt variance in
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let min_val = Array.min_elt result ~compare:Float.compare |> Option.value ~default:0.0 in
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let max_val = Array.max_elt result ~compare:Float.compare |> Option.value ~default:0.0 in
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(* Create histogram with dynamic range *)
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let histogram_min = Float.max (-4.0) (min_val -. 0.5) in
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let histogram_max = Float.min 4.0 (max_val +. 0.5) in
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let num_bins = 30 in
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let bins = create_histogram result ~num_bins ~min_val:histogram_min ~max_val:histogram_max in
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print_histogram bins ~title:"Normal Distribution N(0,1) Histogram" ~max_width:40;
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printf "\nStatistics:\n";
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printf " Mean: %.4f (expected: ~0.0)\n" mean;
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printf " Std Dev: %.4f (expected: ~1.0)\n" std_dev;
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printf " Min: %.4f\n" min_val;
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printf " Max: %.4f\n" max_val;
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(* Check what percentage falls within standard deviations *)
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let within_1_std =
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Array.count result ~f:(fun x -> Float.(abs x <= 1.0))
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in
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let within_2_std =
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Array.count result ~f:(fun x -> Float.(abs x <= 2.0))
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in
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let within_3_std =
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Array.count result ~f:(fun x -> Float.(abs x <= 3.0))
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in
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printf " Within 1 std dev: %.1f%% (expected: ~68.3%%)\n"
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(Float.of_int within_1_std /. Float.of_int (Array.length result) *. 100.0);
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printf " Within 2 std dev: %.1f%% (expected: ~95.4%%)\n"
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(Float.of_int within_2_std /. Float.of_int (Array.length result) *. 100.0);
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printf " Within 3 std dev: %.1f%% (expected: ~99.7%%)\n"
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(Float.of_int within_3_std /. Float.of_int (Array.length result) *. 100.0);
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(* Normality test using skewness and kurtosis *)
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let skewness =
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let sum_cubed = Array.fold result ~init:0.0 ~f:(fun acc x ->
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let diff = x -. mean in
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acc +. (diff *. diff *. diff))
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in
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sum_cubed /. (Float.of_int (Array.length result) *. std_dev *. std_dev *. std_dev)
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in
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let kurtosis =
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let sum_fourth = Array.fold result ~init:0.0 ~f:(fun acc x ->
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let diff = x -. mean in
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let diff2 = diff *. diff in
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acc +. (diff2 *. diff2))
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in
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(sum_fourth /. (Float.of_int (Array.length result) *. std_dev *. std_dev *. std_dev *. std_dev)) -. 3.0
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in
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printf " Skewness: %.4f (expected: ~0.0)\n" skewness;
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printf " Excess Kurtosis: %.4f (expected: ~0.0)\n" kurtosis
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let test_batched_generation_consistency () =
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Tensor.unsafe_reinitialize ();
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let ctx = Context.auto () in
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let module O = TDSL.O in
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(* Test that batched generation gives consistent results *)
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let batch_size = 100 in
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let num_batches = 10 in
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printf "\nBatched Generation Consistency Test\n";
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printf "====================================\n";
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(* Generate values in batches and check they don't repeat across batches *)
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let all_uniform_values = ref [||] in
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let all_normal_values = ref [||] in
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for _batch = 0 to num_batches - 1 do
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(* Each batch uses its own counter range - values are just seeds *)
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let counter = TDSL.range batch_size in
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(* Generate uniform batch *)
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let uniform_batch = O.uniform_at counter in
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Ir.Tnode.update_prec uniform_batch.value Ir.Ops.single;
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Ocannl.Train.set_hosted uniform_batch.value;
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ignore (Ocannl.Train.forward_once ctx uniform_batch);
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let uniform_result = Ir.Tnode.get_values uniform_batch.value in
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all_uniform_values := Array.append !all_uniform_values uniform_result;
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(* Generate normal batch *)
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let normal_batch = O.normal_at counter in
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Ir.Tnode.update_prec normal_batch.value Ir.Ops.single;
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Ocannl.Train.set_hosted normal_batch.value;
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ignore (Ocannl.Train.forward_once ctx normal_batch);
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let normal_result = Ir.Tnode.get_values normal_batch.value in
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all_normal_values := Array.append !all_normal_values normal_result
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done;
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(* Check for uniqueness (with small tolerance for floating point) *)
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let count_unique arr =
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let sorted = Array.copy arr in
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Array.sort sorted ~compare:Float.compare;
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let unique = ref 1 in
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for i = 1 to Array.length sorted - 1 do
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let diff = Float.abs (sorted.(i) -. sorted.(i-1)) in
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if Float.(diff > 1e-7) then
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unique := !unique + 1
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done;
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!unique
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in
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let total_values = batch_size * num_batches in
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let unique_uniform = count_unique !all_uniform_values in
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let unique_normal = count_unique !all_normal_values in
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printf "Generated %d values in %d batches of %d\n" total_values num_batches batch_size;
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printf "Uniform values: %d unique out of %d (%.1f%%)\n"
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unique_uniform total_values
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(Float.of_int unique_uniform /. Float.of_int total_values *. 100.0);
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printf "Normal values: %d unique out of %d (%.1f%%)\n"
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unique_normal total_values
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(Float.of_int unique_normal /. Float.of_int total_values *. 100.0);
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(* Verify batch consistency of statistical properties *)
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let batch_means_uniform = Array.create ~len:num_batches 0.0 in
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let batch_means_normal = Array.create ~len:num_batches 0.0 in
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for batch = 0 to num_batches - 1 do
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let start_idx = batch * batch_size in
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let uniform_batch = Array.sub !all_uniform_values ~pos:start_idx ~len:batch_size in
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let normal_batch = Array.sub !all_normal_values ~pos:start_idx ~len:batch_size in
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batch_means_uniform.(batch) <-
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Array.fold uniform_batch ~init:0.0 ~f:(+.) /. Float.of_int batch_size;
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batch_means_normal.(batch) <-
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Array.fold normal_batch ~init:0.0 ~f:(+.) /. Float.of_int batch_size
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done;
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let mean_of_means_uniform =
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Array.fold batch_means_uniform ~init:0.0 ~f:(+.) /. Float.of_int num_batches
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in
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let mean_of_means_normal =
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Array.fold batch_means_normal ~init:0.0 ~f:(+.) /. Float.of_int num_batches
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in
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let std_of_means_uniform =
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let diff_sum = Array.fold batch_means_uniform ~init:0.0 ~f:(fun acc x ->
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let diff = x -. mean_of_means_uniform in
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acc +. (diff *. diff)) in
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Float.sqrt (diff_sum /. Float.of_int num_batches)
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in
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let std_of_means_normal =
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let diff_sum = Array.fold batch_means_normal ~init:0.0 ~f:(fun acc x ->
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let diff = x -. mean_of_means_normal in
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acc +. (diff *. diff)) in
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Float.sqrt (diff_sum /. Float.of_int num_batches)
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in
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printf "\nBatch means consistency:\n";
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printf " Uniform: mean of batch means = %.4f, std = %.4f\n"
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mean_of_means_uniform std_of_means_uniform;
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printf " Normal: mean of batch means = %.4f, std = %.4f\n"
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mean_of_means_normal std_of_means_normal
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let () =
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test_uniform_at_histogram ();
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printf "\n";
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test_normal_at_histogram ();
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printf "\n";
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test_batched_generation_consistency ()

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