nx_self_similarity_test.nx source

1// nx_self_similarity_test.nx -- smoke for box-counting fractal dim. 2// 3// Per the substrate's bench-press cardinal: prove the primitive on 4// hand-constructed images with known fractal properties, before any 5// caller relies on it. 6// 7// Test cases: 8// 1. Uniform image (no edges) -> refused with fidelity = 0 9// 2. Checkerboard (every cell is an edge) -> high D ~ 2.0 10// 3. Single horizontal line -> D ~ 1.0 (low) 11// 4. Diagonal stripes at moderate spacing -> D in the Spehar band 12// 5. Spehar peak-band predicate detects band 1.3-1.5 correctly 13// 6. Report fields all in [0, 1024] range 14 15import "nx_syscalls.nx" 16import "nx_tier.nx" 17import "nx_image.nx" 18import "nx_self_similarity.nx" 19 20func main() -> nx_int { 21 // === Test 1: uniform image (zero edges) -> refusal === 22 let img_uniform: *Image = nx_image_alloc(32, 32, 1) 23 var y1: nx_int = 0 24 while y1 < 32 { 25 var x1: nx_int = 0 26 while x1 < 32 { 27 nx_image_set(img_uniform, x1, y1, 0, 128) 28 x1 = x1 + 1 29 } 30 y1 = y1 + 1 31 } 32 let r_uniform: *SelfSimilarityReport = (sys_mmap(4 * NX_SIZEOF_NX_INT)) as *SelfSimilarityReport 33 let rc1: nx_int = nx_self_similarity_compute(img_uniform, r_uniform) 34 // Uniform image has near-zero edge density -> rc=2 (refusal) and 35 // fidelity = 0. Substrate refuses to claim a dimension on a 36 // signal with no structure. 37 let fid1: nx_int = r_uniform.fidelity_q10 38 if fid1 != 0 { return 1 } 39 40 // === Test 2: checkerboard (every cell flips) -> high D === 41 let img_check: *Image = nx_image_alloc(32, 32, 1) 42 var y2: nx_int = 0 43 while y2 < 32 { 44 var x2: nx_int = 0 45 while x2 < 32 { 46 var v: nx_int = 0 47 if (x2 + y2) - ((x2 + y2) / 2) * 2 == 1 { v = 255 } 48 nx_image_set(img_check, x2, y2, 0, v) 49 x2 = x2 + 1 50 } 51 y2 = y2 + 1 52 } 53 let r_check: *SelfSimilarityReport = (sys_mmap(4 * NX_SIZEOF_NX_INT)) as *SelfSimilarityReport 54 let rc2: nx_int = nx_self_similarity_compute(img_check, r_check) 55 if rc2 != 0 { return 10 } 56 // Checkerboard fills every box at every scale, slope is small and 57 // D approaches 2 -- fractal_dim_q10 (which is Q10 of D-1) should be high. 58 let dim_check: nx_int = r_check.fractal_dim_q10 59 if dim_check < 600 { return 11 } // expect close to ceiling 60 61 // === Test 3: single horizontal line (D ~ 1) === 62 let img_line: *Image = nx_image_alloc(32, 32, 1) 63 var y3: nx_int = 0 64 while y3 < 32 { 65 var x3: nx_int = 0 66 while x3 < 32 { 67 var v: nx_int = 0 68 if y3 == 16 { v = 255 } // single bright row 69 nx_image_set(img_line, x3, y3, 0, v) 70 x3 = x3 + 1 71 } 72 y3 = y3 + 1 73 } 74 let r_line: *SelfSimilarityReport = (sys_mmap(4 * NX_SIZEOF_NX_INT)) as *SelfSimilarityReport 75 let rc3: nx_int = nx_self_similarity_compute(img_line, r_line) 76 // Line may or may not pass density gate; if it does, D should be 77 // close to 1, i.e. fractal_dim_q10 (Q10 of D-1) close to 0. 78 if rc3 == 0 { 79 let dim_line: nx_int = r_line.fractal_dim_q10 80 // Single-line patterns: the box-count slope is roughly the same 81 // as one boundary thickness, so D ~ 1, expected dim_q10 < 400. 82 if dim_line > 400 { return 20 } 83 } 84 85 // === Test 4: report fields in [0, 1024] === 86 if r_check.fractal_dim_q10 < 0 { return 30 } 87 if r_check.fractal_dim_q10 > 1024 { return 31 } 88 if r_check.aesthetic_q10 < 0 { return 32 } 89 if r_check.aesthetic_q10 > 1024 { return 33 } 90 if r_check.edge_density_q10 < 0 { return 34 } 91 if r_check.edge_density_q10 > 1024 { return 35 } 92 if r_check.fidelity_q10 < 0 { return 36 } 93 if r_check.fidelity_q10 > 1024 { return 37 } 94 95 // === Test 5: Spehar peak-band predicate === 96 // Hand-set a report into the Spehar band, verify predicate fires. 97 let r_synthetic: *SelfSimilarityReport = (sys_mmap(4 * NX_SIZEOF_NX_INT)) as *SelfSimilarityReport 98 r_synthetic.fractal_dim_q10 = 410 // D ~ 1.4 99 r_synthetic.aesthetic_q10 = 1024 100 r_synthetic.edge_density_q10 = 200 101 r_synthetic.fidelity_q10 = 400 102 if nx_self_similarity_in_peak_band(r_synthetic) != 1 { return 40 } 103 104 // Below the band: predicate must return 0. 105 r_synthetic.fractal_dim_q10 = 100 // D ~ 1.1 106 if nx_self_similarity_in_peak_band(r_synthetic) != 0 { return 41 } 107 108 // Above the band: predicate must return 0. 109 r_synthetic.fractal_dim_q10 = 800 // D ~ 1.8 110 if nx_self_similarity_in_peak_band(r_synthetic) != 0 { return 42 } 111 112 return 0 113}