repl.txt (4037B)
1 2 {{alias}}( N, correction, x, stride ) 3 Computes the variance of a strided array ignoring `NaN` values. 4 5 The `N` and `stride` parameters determine which elements in `x` are accessed 6 at runtime. 7 8 Indexing is relative to the first index. To introduce an offset, use a typed 9 array view. 10 11 If `N <= 0`, the function returns `NaN`. 12 13 If every indexed element is `NaN`, the function returns `NaN`. 14 15 Parameters 16 ---------- 17 N: integer 18 Number of indexed elements. 19 20 correction: number 21 Degrees of freedom adjustment. Setting this parameter to a value other 22 than `0` has the effect of adjusting the divisor during the calculation 23 of the variance according to `n - c` where `c` corresponds to the 24 provided degrees of freedom adjustment and `n` corresponds to the number 25 of non-`NaN` indexed elements. When computing the variance of a 26 population, setting this parameter to `0` is the standard choice (i.e., 27 the provided array contains data constituting an entire population). 28 When computing the unbiased sample variance, setting this parameter to 29 `1` is the standard choice (i.e., the provided array contains data 30 sampled from a larger population; this is commonly referred to as 31 Bessel's correction). 32 33 x: Array<number>|TypedArray 34 Input array. 35 36 stride: integer 37 Index increment. 38 39 Returns 40 ------- 41 out: number 42 The variance. 43 44 Examples 45 -------- 46 // Standard Usage: 47 > var x = [ 1.0, -2.0, NaN, 2.0 ]; 48 > {{alias}}( x.length, 1, x, 1 ) 49 ~4.3333 50 51 // Using `N` and `stride` parameters: 52 > x = [ -2.0, 1.0, 1.0, -5.0, 2.0, -1.0 ]; 53 > var N = {{alias:@stdlib/math/base/special/floor}}( x.length / 2 ); 54 > var stride = 2; 55 > {{alias}}( N, 1, x, stride ) 56 ~4.3333 57 58 // Using view offsets: 59 > var x0 = new {{alias:@stdlib/array/float64}}( [ 1.0, -2.0, 3.0, 2.0, 5.0, -1.0 ] ); 60 > var x1 = new {{alias:@stdlib/array/float64}}( x0.buffer, x0.BYTES_PER_ELEMENT*1 ); 61 > N = {{alias:@stdlib/math/base/special/floor}}( x0.length / 2 ); 62 > stride = 2; 63 > {{alias}}( N, 1, x1, stride ) 64 ~4.3333 65 66 {{alias}}.ndarray( N, correction, x, stride, offset ) 67 Computes the variance of a strided array ignoring `NaN` values and using 68 alternative indexing semantics. 69 70 While typed array views mandate a view offset based on the underlying 71 buffer, the `offset` parameter supports indexing semantics based on a 72 starting index. 73 74 Parameters 75 ---------- 76 N: integer 77 Number of indexed elements. 78 79 correction: number 80 Degrees of freedom adjustment. Setting this parameter to a value other 81 than `0` has the effect of adjusting the divisor during the calculation 82 of the variance according to `n - c` where `c` corresponds to the 83 provided degrees of freedom adjustment and `n` corresponds to the number 84 of non-`NaN` indexed elements. When computing the variance of a 85 population, setting this parameter to `0` is the standard choice (i.e., 86 the provided array contains data constituting an entire population). 87 When computing the unbiased sample variance, setting this parameter to 88 `1` is the standard choice (i.e., the provided array contains data 89 sampled from a larger population; this is commonly referred to as 90 Bessel's correction). 91 92 x: Array<number>|TypedArray 93 Input array. 94 95 stride: integer 96 Index increment. 97 98 offset: integer 99 Starting index. 100 101 Returns 102 ------- 103 out: number 104 The variance. 105 106 Examples 107 -------- 108 // Standard Usage: 109 > var x = [ 1.0, -2.0, NaN, 2.0 ]; 110 > {{alias}}.ndarray( x.length, 1, x, 1, 0 ) 111 ~4.3333 112 113 // Using offset parameter: 114 > var x = [ 1.0, -2.0, 3.0, 2.0, 5.0, -1.0 ]; 115 > var N = {{alias:@stdlib/math/base/special/floor}}( x.length / 2 ); 116 > {{alias}}.ndarray( N, 1, x, 2, 1 ) 117 ~4.3333 118 119 See Also 120 -------- 121