| Line | Branch | Exec | Source |
|---|---|---|---|
| 1 | module athena__activation_softmax | ||
| 2 | !! Module containing implementation of the softmax activation function | ||
| 3 | !! | ||
| 4 | !! This module implements softmax for converting logits into probability | ||
| 5 | !! distributions. Commonly used for multi-class classification. | ||
| 6 | !! | ||
| 7 | !! Mathematical operation: | ||
| 8 | !! \[ \text{softmax}(\mathbf{x})_i = \frac{e^{x_i}}{\sum_{j=1}^{n} e^{x_j}} \] | ||
| 9 | !! | ||
| 10 | !! Properties: | ||
| 11 | !! - Outputs sum to 1: \(\sum_{i=1}^{n} \text{softmax}(\mathbf{x})_i = 1\) | ||
| 12 | !! - All outputs in range \((0, 1)\) | ||
| 13 | !! - Preserves ordering: \(x_i > x_j \Rightarrow f(x_i) > f(x_j)\) | ||
| 14 | !! - Translation invariant: \(\text{softmax}(\mathbf{x}+c) = \text{softmax}(\mathbf{x})\) | ||
| 15 | !! | ||
| 16 | !! Derivative (Jacobian): | ||
| 17 | !! \[ \frac{\partial f_i}{\partial x_j} = f_i(\delta_{ij} - f_j) \] | ||
| 18 | !! where \(\delta_{ij}\) is the Kronecker delta | ||
| 19 | use coreutils, only: real32, print_warning | ||
| 20 | use diffstruc, only: array_type, operator(*) | ||
| 21 | use athena__diffstruc_extd, only: softmax | ||
| 22 | use athena__misc_types, only: base_actv_type | ||
| 23 | use athena__misc_types, only: onnx_attribute_type | ||
| 24 | implicit none | ||
| 25 | |||
| 26 | |||
| 27 | private | ||
| 28 | |||
| 29 | public :: softmax_actv_type, create_from_onnx_softmax_activation | ||
| 30 | |||
| 31 | |||
| 32 | type, extends(base_actv_type) :: softmax_actv_type | ||
| 33 | !! Type for softmax activation function with overloaded procedures | ||
| 34 | contains | ||
| 35 | procedure, pass(this) :: apply => apply_softmax | ||
| 36 | procedure, pass(this) :: reset => reset_softmax | ||
| 37 | procedure, pass(this) :: apply_attributes => apply_attributes_softmax | ||
| 38 | procedure, pass(this) :: export_attributes => export_attributes_softmax | ||
| 39 | end type softmax_actv_type | ||
| 40 | |||
| 41 | interface softmax_actv_type | ||
| 42 | procedure initialise | ||
| 43 | end interface softmax_actv_type | ||
| 44 | |||
| 45 | |||
| 46 | |||
| 47 | contains | ||
| 48 | |||
| 49 | !############################################################################### | ||
| 50 | − | function initialise(scale, attributes) result(activation) | |
| 51 | !! Initialise a softmax activation function | ||
| 52 | implicit none | ||
| 53 | |||
| 54 | ! Arguments | ||
| 55 | real(real32), intent(in), optional :: scale | ||
| 56 | !! Optional scale factor for activation output | ||
| 57 | type(onnx_attribute_type), dimension(:), intent(in), optional :: attributes | ||
| 58 | !! Optional array of ONNX attributes | ||
| 59 | type(softmax_actv_type) :: activation | ||
| 60 | !! Softmax activation type | ||
| 61 | |||
| 62 | − | call activation%reset() | |
| 63 | |||
| 64 | − | if(present(scale)) activation%scale = scale | |
| 65 | − | if(abs(activation%scale-1._real32) .gt. 1.e-6_real32)then | |
| 66 | − | activation%apply_scaling = .true. | |
| 67 | end if | ||
| 68 | |||
| 69 | − | if(present(attributes)) then | |
| 70 | − | call activation%apply_attributes(attributes) | |
| 71 | end if | ||
| 72 | |||
| 73 | − | end function initialise | |
| 74 | !------------------------------------------------------------------------------- | ||
| 75 | − | pure subroutine reset_softmax(this) | |
| 76 | !! Reset softmax activation function attributes and variables | ||
| 77 | implicit none | ||
| 78 | |||
| 79 | ! Arguments | ||
| 80 | class(softmax_actv_type), intent(inout) :: this | ||
| 81 | !! Softmax activation type | ||
| 82 | |||
| 83 | − | this%name = "softmax" | |
| 84 | − | this%scale = 1._real32 | |
| 85 | − | this%threshold = 0._real32 | |
| 86 | − | this%apply_scaling = .false. | |
| 87 | |||
| 88 | − | end subroutine reset_softmax | |
| 89 | !------------------------------------------------------------------------------- | ||
| 90 | − | function create_from_onnx_softmax_activation(attributes) result(activation) | |
| 91 | !! Create softmax activation function from ONNX attributes | ||
| 92 | implicit none | ||
| 93 | |||
| 94 | ! Arguments | ||
| 95 | type(onnx_attribute_type), dimension(:), intent(in) :: attributes | ||
| 96 | !! Array of ONNX attributes | ||
| 97 | |||
| 98 | class(base_actv_type), allocatable :: activation | ||
| 99 | !! Instance of activation type | ||
| 100 | |||
| 101 | − | allocate(activation, source = softmax_actv_type(attributes = attributes)) | |
| 102 | |||
| 103 | − | end function create_from_onnx_softmax_activation | |
| 104 | !############################################################################### | ||
| 105 | |||
| 106 | |||
| 107 | !############################################################################### | ||
| 108 | − | subroutine apply_attributes_softmax(this, attributes) | |
| 109 | !! Load ONNX attributes into softmax activation function | ||
| 110 | implicit none | ||
| 111 | |||
| 112 | ! Arguments | ||
| 113 | class(softmax_actv_type), intent(inout) :: this | ||
| 114 | !! Softmax activation type | ||
| 115 | type(onnx_attribute_type), dimension(:), intent(in) :: attributes | ||
| 116 | !! Array of ONNX attributes | ||
| 117 | |||
| 118 | ! Local variables | ||
| 119 | integer :: i | ||
| 120 | !! Loop variable | ||
| 121 | |||
| 122 | ! Load provided attributes | ||
| 123 | − | do i=1, size(attributes,dim=1) | |
| 124 | − | select case(trim(attributes(i)%name)) | |
| 125 | case("scale") | ||
| 126 | − | read(attributes(i)%val,*) this%scale | |
| 127 | − | if(abs(this%scale-1._real32) .gt. 1.e-6_real32)then | |
| 128 | − | this%apply_scaling = .true. | |
| 129 | else | ||
| 130 | − | this%apply_scaling = .false. | |
| 131 | end if | ||
| 132 | case("name") | ||
| 133 | − | if(trim(attributes(i)%val) .ne. trim(this%name)) then | |
| 134 | call print_warning( & | ||
| 135 | 'Softmax activation: name attribute "' // & | ||
| 136 | − | trim(attributes(i)%val) // & | |
| 137 | '"" does not match expected "' // trim(this%name)//'"' & | ||
| 138 | − | ) | |
| 139 | |||
| 140 | end if | ||
| 141 | case default | ||
| 142 | call print_warning( & | ||
| 143 | 'Softmax activation: unknown attribute '// & | ||
| 144 | − | trim(attributes(i)%name) & | |
| 145 | − | ) | |
| 146 | end select | ||
| 147 | end do | ||
| 148 | |||
| 149 | − | end subroutine apply_attributes_softmax | |
| 150 | !############################################################################### | ||
| 151 | |||
| 152 | |||
| 153 | !############################################################################### | ||
| 154 | − | pure function export_attributes_softmax(this) result(attributes) | |
| 155 | !! Export softmax activation function attributes as ONNX attributes | ||
| 156 | implicit none | ||
| 157 | |||
| 158 | ! Arguments | ||
| 159 | class(softmax_actv_type), intent(in) :: this | ||
| 160 | !! Softmax activation type | ||
| 161 | type(onnx_attribute_type), allocatable, dimension(:) :: attributes | ||
| 162 | !! Array of ONNX attributes | ||
| 163 | |||
| 164 | ! Local variables | ||
| 165 | character(50) :: buffer | ||
| 166 | !! Temporary string buffer | ||
| 167 | |||
| 168 | − | allocate(attributes(2)) | |
| 169 | |||
| 170 | − | write(buffer, '(A)') this%name | |
| 171 | − | attributes(1) = onnx_attribute_type( & | |
| 172 | − | "name", "string", trim(adjustl(buffer)) ) | |
| 173 | |||
| 174 | − | write(buffer, '(F10.6)') this%scale | |
| 175 | − | attributes(2) = onnx_attribute_type( & | |
| 176 | − | "scale", "float", trim(adjustl(buffer)) ) | |
| 177 | |||
| 178 | − | end function export_attributes_softmax | |
| 179 | !############################################################################### | ||
| 180 | |||
| 181 | |||
| 182 | !############################################################################### | ||
| 183 | − | function apply_softmax(this, val) result(output) | |
| 184 | !! Apply softmax activation to 1D array | ||
| 185 | !! | ||
| 186 | !! Computes: f = exp(x-max)/sum(exp(x-max)) | ||
| 187 | implicit none | ||
| 188 | |||
| 189 | ! Arguments | ||
| 190 | class(softmax_actv_type), intent(in) :: this | ||
| 191 | !! Softmax activation type | ||
| 192 | type(array_type), intent(in) :: val | ||
| 193 | !! Input values | ||
| 194 | type(array_type), pointer :: output | ||
| 195 | !! Normalised probability distribution output | ||
| 196 | |||
| 197 | !! compute softmax values | ||
| 198 | − | if(this%apply_scaling)then | |
| 199 | − | output => softmax(val, dim=2) * this%scale | |
| 200 | else | ||
| 201 | − | output => softmax(val, dim=2) | |
| 202 | end if | ||
| 203 | − | end function apply_softmax | |
| 204 | !############################################################################### | ||
| 205 | |||
| 206 | − | end module athena__activation_softmax | |
| 207 |