# simd_double2 A vector of two 64-bit floating-point elements. ``` typealias simd_double2 = SIMD2 ``` ## Topics ### Functions to Create Two-Element Vectors From Other Vectors [`simd_make_double2(_:)`](/documentation/simd/simd_make_double2(_:)-3qby3) Returns a new vector from the specified vector. [`simd_make_double2(_:)`](/documentation/simd/simd_make_double2(_:)-3tt38) Returns a new vector by truncating the specified three-element vector. [`simd_make_double2(_:)`](/documentation/simd/simd_make_double2(_:)-3hpld) Returns a new vector by truncating the specified four-element vector. [`simd_make_double2(_:)`](/documentation/simd/simd_make_double2(_:)-4o3ot) Returns a new vector by truncating the specified eight-element vector. [`simd_make_double2(_:_:)`](/documentation/simd/simd_make_double2(_:_:)) Returns a new vector from the specified vectors. [`vector2`](/documentation/simd/vector2-8cpbh) Returns a new vector from the specified vectors. ### Functions to Create Two-Element Vectors From Scalar Values [`simd_make_double2(_:)`](/documentation/simd/simd_make_double2(_:)-r6xz) Returns a new vector with the first element set to a scalar value, and other elements set to zero. [`simd_make_double2_undef(_:)`](/documentation/simd/simd_make_double2_undef(_:)) Returns a new vector with the first element set to a scalar value, and other elements undefined. ### Functions to Create Three-Element Vectors From Vectors of Other Types [`simd_double`](/documentation/simd/simd_double-531gc) Returns a new vector from the specified vector of 8-bit, signed-integer elements. [`simd_double`](/documentation/simd/simd_double-53bbw) Returns a new vector from the specified vector of 8-bit, unsigned-integer elements. [`simd_double`](/documentation/simd/simd_double-536fw) Returns a new vector from the specified vector of 16-bit, signed-integer elements. [`simd_double`](/documentation/simd/simd_double-53gf0) Returns a new vector from the specified vector of 16-bit, unsigned-integer elements. [`simd_double`](/documentation/simd/simd_double-534k4) Returns a new vector from the specified vector of 32-bit, signed-integer elements. [`simd_double`](/documentation/simd/simd_double-53ej8) Returns a new vector from the specified vector of 32-bit, unsigned-integer elements. [`simd_double`](/documentation/simd/simd_double-5365s) Returns a new vector from the specified vector of 64-bit, signed-integer elements. [`simd_double`](/documentation/simd/simd_double-53fzk) Returns a new vector from the specified vector of 64-bit, unsigned-integer elements. [`simd_double`](/documentation/simd/simd_double-53czc) Returns a new vector from the specified vector of 32-bit, floating-point elements. [`simd_double`](/documentation/simd/simd_double-53di8) Returns a new vector from the specified vector of 64-bit, floating-point elements. ### Common Functions [`simd_abs(_:)`](/documentation/simd/simd_abs(_:)-8869e) Returns the absolute value of each element in a vector. [`abs(_:)`](/documentation/simd/abs(_:)-1p8t7) Returns the absolute value of each element in a vector. [`simd_clamp(_:_:_:)`](/documentation/simd/simd_clamp(_:_:_:)-6puwa) Returns each element in a vector clamped to a specified range. [`clamp(_:min:max:)`](/documentation/simd/clamp(_:min:max:)-7n2jv) Returns each element in a vector clamped to a specified range. [`clamp(_:min:max:)`](/documentation/simd/clamp(_:min:max:)-6d1s7) Returns each element in a vector clamped to a specified range. [`simd_equal(_:_:)`](/documentation/simd/simd_equal(_:_:)-vmn4) Returns true if every element in a vector is exactly equal to the corresponding element in a second vector, and otherwise returns false. [`simd_fract(_:)`](/documentation/simd/simd_fract(_:)-42i3r) Returns the fractional part of each element in a vector. [`fract(_:)`](/documentation/simd/fract(_:)-2gjrn) Returns the fractional part of each element in a vector. [`simd_sign(_:)`](/documentation/simd/simd_sign(_:)-6jlx9) Returns the sign of each element in a vector. [`sign(_:)`](/documentation/simd/sign(_:)-5fczz) Returns the sign of each element in a vector. [`step(_:edge:)`](/documentation/simd/step(_:edge:)-2qauk) Returns zero for each element in a vector less than a specified edge, and otherwise returns one. [`simd_step(_:_:)`](/documentation/simd/simd_step(_:_:)-8jlf2) Returns zero for each element in a vector less than a specified edge, and otherwise returns one. ### Reduce Functions [`simd_reduce_add(_:)`](/documentation/simd/simd_reduce_add(_:)-2q09i) Returns the sum of all elements in a vector. [`reduce_add(_:)`](/documentation/simd/reduce_add(_:)-8iwo6) Returns the sum of all elements in a vector. [`simd_reduce_max(_:)`](/documentation/simd/simd_reduce_max(_:)-4kinw) Returns the maximum value in a vector. [`reduce_max(_:)`](/documentation/simd/reduce_max(_:)-3rmpx) Returns the maximum value in a vector. [`simd_reduce_min(_:)`](/documentation/simd/simd_reduce_min(_:)-49t1o) Returns the minimum value in a vector. [`reduce_min(_:)`](/documentation/simd/reduce_min(_:)-6mev7) Returns the minimum value in a vector. ### Interpolation Functions [`simd_smoothstep(_:_:_:)`](/documentation/simd/simd_smoothstep(_:_:_:)-e0ov) Returns an element-wise smoothly interpolated value between two vectors. [`smoothstep(_:edge0:edge1:)`](/documentation/simd/smoothstep(_:edge0:edge1:)-2wqo9) Returns an element-wise smoothly interpolated value between two vectors. [`simd_mix(_:_:_:)`](/documentation/simd/simd_mix(_:_:_:)-v083) Returns an element-wise linearly interpolated value between two vectors. [`mix(_:_:t:)`](/documentation/simd/mix(_:_:t:)-7bjg5) Returns an element-wise linearly interpolated value between two vectors. [`mix(_:_:t:)`](/documentation/simd/mix(_:_:t:)-3hfwb) Returns an element-wise linearly interpolated value between two vectors. ### Extrema Functions [`simd_max(_:_:)`](/documentation/simd/simd_max(_:_:)-1sy2n) Returns the maximum value of each element in a vector. [`max(_:_:)`](/documentation/simd/max(_:_:)-3puhr) Returns the maximum value of each element in a vector. [`max(_:_:)`](/documentation/simd/max(_:_:)-8a5p5) Returns the maximum value of each element in a vector. [`fmax(_:_:)`](/documentation/simd/fmax(_:_:)-15te9) Returns the maximum value of each element in a vector. [`simd_min(_:_:)`](/documentation/simd/simd_min(_:_:)-9mraz) Returns the minimum value of each element in a vector. [`min(_:_:)`](/documentation/simd/min(_:_:)-4sdw0) Returns the minimum value of each element in a vector. [`min(_:_:)`](/documentation/simd/min(_:_:)-9yz9x) Returns the minimum value of each element in a vector. [`fmin(_:_:)`](/documentation/simd/fmin(_:_:)-39mes) Returns the minimum value of each element in a vector. ### Reciprocal and Reciprocal Square Root Functions [`recip(_:)`](/documentation/simd/recip(_:)-43mv7) Returns the reciprocal of each element in a vector. [`simd_recip(_:)`](/documentation/simd/simd_recip(_:)-8nekc) Returns the reciprocal of each element in a vector. [`simd_fast_recip(_:)`](/documentation/simd/simd_fast_recip(_:)-lm0t) Returns the fast reciprocal of each element in a vector. [`simd_precise_recip(_:)`](/documentation/simd/simd_precise_recip(_:)-66n8k) Returns the precise reciprocal of each element in a vector. [`simd_rsqrt(_:)`](/documentation/simd/simd_rsqrt(_:)-ok9s) Returns the reciprocal square root of each element in a vector. [`rsqrt(_:)`](/documentation/simd/rsqrt(_:)-2k5rh) Returns the reciprocal square root of each element in a vector. [`simd_fast_rsqrt(_:)`](/documentation/simd/simd_fast_rsqrt(_:)-84dca) Returns the fast reciprocal square root of each element in a vector. [`simd_precise_rsqrt(_:)`](/documentation/simd/simd_precise_rsqrt(_:)-wrke) Returns the precise reciprocal square root of each element in a vector. ### Exponential and Logarithmic Functions [`exp(_:)`](/documentation/simd/exp(_:)-9nxip) Returns *e* raised to the power of each element in a vector. [`exp2(_:)`](/documentation/simd/exp2(_:)-4y2ne) Returns 2 raised to the power of each element in a vector. [`exp10(_:)`](/documentation/simd/exp10(_:)-4tdos) Returns 10 raised to the power of each element in a vector. [`expm1(_:)`](/documentation/simd/expm1(_:)-9aitr) Returns *eˣ-1* for each element in a vector. [`log(_:)`](/documentation/simd/log(_:)-2ieba) Returns the natural logarithm of each element in a vector. [`log2(_:)`](/documentation/simd/log2(_:)-779eu) Returns the base 2 logarithm of each element in a vector. [`log10(_:)`](/documentation/simd/log10(_:)-337zw) Returns the base 10 logarithm of each element in a vector. [`log1p(_:)`](/documentation/simd/log1p(_:)-40mka) Returns *log(1+x)* of each element in a vector. [`exp`](/documentation/simd/exp) Returns *e* raised to the power of each element in a vector. [`exp2`](/documentation/simd/exp2) Returns 2 raised to the power of each element in a vector. [`exp10`](/documentation/simd/exp10) Returns 10 raised to the power of each element in a vector. [`expm1`](/documentation/simd/expm1) Returns *eˣ-1* for each element in a vector. [`log`](/documentation/simd/log) Returns the natural logarithm of each element in a vector. [`log2`](/documentation/simd/log2) Returns the base 2 logarithm of each element in a vector. [`log10`](/documentation/simd/log10) Returns the base 10 logarithm of each element in a vector. [`log1p`](/documentation/simd/log1p) Returns *log(1+x)* for each element in a vector. ### Geometry Functions [`simd_cross`](/documentation/simd/simd_cross-1dixl) Returns the cross product of two vectors. [`cross(_:_:)`](/documentation/simd/cross(_:_:)-916aw) Returns the cross product of two vectors. [`simd_dot`](/documentation/simd/simd_dot-3r1vl) Returns the dot product of two vectors. [`dot(_:_:)`](/documentation/simd/dot(_:_:)-6ayky) Returns the dot product of two vectors. [`simd_incircle`](/documentation/simd/simd_incircle-8iogb) Tests if a double-precision point lies inside, on, or outside a circle. [`simd_normalize`](/documentation/simd/simd_normalize-9fo1c) Returns a vector pointing in the same direction of the supplied vector, with a length of 1. [`normalize(_:)`](/documentation/simd/normalize(_:)-5mqhk) Returns a vector pointing in the same direction of the supplied vector with a length of 1. [`simd_fast_normalize`](/documentation/simd/simd_fast_normalize-9wy6m) Returns the fast normalized vector. [`simd_precise_normalize`](/documentation/simd/simd_precise_normalize-54dru) Returns the precise normalized vector. [`simd_orient`](/documentation/simd/simd_orient-9fgki) Tests the orientation of the two supplied vectors. [`simd_orient`](/documentation/simd/simd_orient-9b2wf) Tests the orientation of the three supplied vectors. [`simd_project`](/documentation/simd/simd_project-1mg5p) Returns the first vector projected onto the second vector. [`project(_:_:)`](/documentation/simd/project(_:_:)-kai1) Returns the first vector projected onto the second vector. [`simd_fast_project`](/documentation/simd/simd_fast_project-6c68k) Returns the fast projected vector. [`simd_precise_project`](/documentation/simd/simd_precise_project-7t3qn) Returns the precise projected vector. [`simd_reflect`](/documentation/simd/simd_reflect-7c8f9) Returns the reflection direction of an incident vector and a unit normal vector. [`reflect(_:n:)`](/documentation/simd/reflect(_:n:)-3rhgb) Returns the reflection direction of an incident vector and a unit normal vector. [`simd_refract`](/documentation/simd/simd_refract-4ani9) Returns the refraction direction of an incident vector, a unit normal vector, and an index of refraction eta. [`refract(_:n:eta:)`](/documentation/simd/refract(_:n:eta:)-1ghae) Returns the refraction direction of an incident vector, a unit normal vector, and an index of refraction eta. ### Vector Norm Functions [`simd_norm_one`](/documentation/simd/simd_norm_one-10wox) Returns the sum of the absolute values of a vector. [`norm_one(_:)`](/documentation/simd/norm_one(_:)-2uh74) Returns the sum of the absolute values of a vector. [`simd_norm_inf`](/documentation/simd/simd_norm_inf-91byc) Returns the maximum absolute value of a vector. [`norm_inf(_:)`](/documentation/simd/norm_inf(_:)-s3p1) Returns the maximum absolute value of a vector. ### Length and Distance Functions [`simd_length`](/documentation/simd/simd_length-3oaj5) Returns the length of a vector. [`length(_:)`](/documentation/simd/length(_:)-4gxdk) Returns the length of a vector. [`simd_fast_length`](/documentation/simd/simd_fast_length-59e3i) Returns the fast length of a vector. [`simd_precise_length`](/documentation/simd/simd_precise_length-77yjg) Returns the precise length of a vector. [`simd_length_squared`](/documentation/simd/simd_length_squared-3e3uf) Returns the square of the length of a vector. [`length_squared(_:)`](/documentation/simd/length_squared(_:)-8gxz9) Returns the square of the length of a vector. [`distance(_:_:)`](/documentation/simd/distance(_:_:)-1mnxv) Returns the distance between two vectors. [`simd_distance`](/documentation/simd/simd_distance-2d51k) Returns the distance between two vectors. [`simd_fast_distance`](/documentation/simd/simd_fast_distance-3vbs7) Returns the fast distance between two vectors. [`simd_precise_distance`](/documentation/simd/simd_precise_distance-3dnn0) Returns the precise distance between two vectors. [`simd_distance_squared`](/documentation/simd/simd_distance_squared-7xzck) Returns the square of the distance between two vectors. [`distance_squared(_:_:)`](/documentation/simd/distance_squared(_:_:)-56tah) Returns the square of the distance between two vectors. ### Hyperbolic Functions [`acosh(_:)`](/documentation/simd/acosh(_:)-edu) Returns the inverse hyperbolic cosine of each element in a vector. [`asinh(_:)`](/documentation/simd/asinh(_:)-nxaa) Returns the inverse hyperbolic sine of each element in a vector. [`atanh(_:)`](/documentation/simd/atanh(_:)-5l8ss) Returns the inverse hyperbolic tangent of each element in a vector. [`cosh(_:)`](/documentation/simd/cosh(_:)-303ot) Returns the hyperbolic cosine of each element in a vector. [`sinh(_:)`](/documentation/simd/sinh(_:)-5gx9h) Returns the hyperbolic sine of each element in a vector. [`tanh(_:)`](/documentation/simd/tanh(_:)-739hq) Returns the hyperbolic tangent of each element in a vector. [`acosh`](/documentation/simd/acosh) Returns the inverse hyperbolic cosine of each element in a vector. [`asinh`](/documentation/simd/asinh) Returns the inverse hyperbolic sine of each element in a vector. [`atanh`](/documentation/simd/atanh) Returns the inverse hyperbolic tangent of each element in a vector. [`cosh`](/documentation/simd/cosh) Returns the hyperbolic cosine of each element in a vector. [`sinh`](/documentation/simd/sinh) Returns the hyperbolic sine of each element in a vector. [`tanh`](/documentation/simd/tanh) Returns the hyperbolic tangent of each element in a vector. ### Logic Functions [`simd_select(_:_:_:)`](/documentation/simd/simd_select(_:_:_:)-7sz6k) Returns a vector that contains elements from either the first or second parameter, based on the corresponding element’s high-order bit in the mask. [`simd_bitselect(_:_:_:)`](/documentation/simd/simd_bitselect(_:_:_:)-3ys1a) Returns a vector that contains elements from either the first or second parameter, based on the corresponding element in the third parameter. ### Math Functions [`cbrt(_:)`](/documentation/simd/cbrt(_:)-75bqn) Returns the cube root of each element in a vector. [`ceil(_:)`](/documentation/simd/ceil(_:)-cu6z) Returns the ceiling of each element in a vector. [`erf(_:)`](/documentation/simd/erf(_:)-7tfrz) Returns the error function for each element in a vector. [`erfc(_:)`](/documentation/simd/erfc(_:)-8i2r6) Returns the complementary error function for each element in a vector. [`floor(_:)`](/documentation/simd/floor(_:)-21h1y) [`fma(_:_:_:)`](/documentation/simd/fma(_:_:_:)-4fxau) Returns the multiply-add result for corresponding elements in three vectors. [`fmod(_:_:)`](/documentation/simd/fmod(_:_:)-81hr1) Returns the modulus after dividing each element in a vector by the corresponding element in a second vector. [`hypot(_:_:)`](/documentation/simd/hypot(_:_:)-9ecpz) Returns the hypotenuse of a right-angled triangle with the sides that are adjacent to the right angle that two vectors define. [`lgamma(_:)`](/documentation/simd/lgamma(_:)-697vf) Returns the natural logarithm of the absolute value of the gamma function of each element in a vector. [`nextafter(_:_:)`](/documentation/simd/nextafter(_:_:)-6qeuz) Returns the next representable value of each element in a vector in the direction of the corresponding element in a second vector. [`pow(_:_:)`](/documentation/simd/pow(_:_:)-2ov0n) Returns each element in a vector raised to the power of the corresponding element in a second vector. [`remainder(_:_:)`](/documentation/simd/remainder(_:_:)-1l80m) Returns the remainder after dividing each element in an array by the corresponding element in a second array of double-precision values. [`round(_:)`](/documentation/simd/round(_:)-1ith) Returns each element in a vector rounded to the nearest integer. [`cbrt`](/documentation/simd/cbrt) Returns the cube root of each element in a vector. [`copysign`](/documentation/simd/copysign) Returns each element of a vector, with the sign of the corresponding element in a second vector. [`erf`](/documentation/simd/erf) Returns the error function for each element in a vector. [`erfc`](/documentation/simd/erfc) Returns the complementary error function for each element in a vector. [`fabs`](/documentation/simd/fabs) Returns the absolute value of each element in a vector. [`fdim`](/documentation/simd/fdim) Returns the positive difference between corresponding elements in two vectors. [`fma`](/documentation/simd/fma) Returns the multiply-add result for corresponding elements in three vectors. [`fmod`](/documentation/simd/fmod) Returns the modulus after dividing each element in a vector by the corresponding element in a second vector. [`hypot`](/documentation/simd/hypot) Returns the hypotenuse of a right-angled triangle with the sides that are adjacent to the right angle that two vectors define. [`nextafter`](/documentation/simd/nextafter) Returns the next representable value of each element in a vector in the direction of the corresponding element in a second vector. [`pow`](/documentation/simd/pow) Returns each element in a vector raised to the power of the corresponding element in a second vector. [`remainder`](/documentation/simd/remainder) Returns the remainder after dividing each element in an array by the corresponding element in a second array of double-precision values. [`rint`](/documentation/simd/rint) Returns each element in a vector rounded to the nearest integer in the specified direction. [`round`](/documentation/simd/round) Returns each element in a vector rounded to the nearest integer. [`simd_muladd(_:_:_:)`](/documentation/simd/simd_muladd(_:_:_:)-o9lv) Returns the multiply-add result for corresponding elements in three vectors. [`tgamma(_:)`](/documentation/simd/tgamma(_:)-3id8t) Returns the gamma function for each element in a vector. [`trunc(_:)`](/documentation/simd/trunc(_:)-1xvcu) Returns each element in a vector rounded toward zero to the nearest integer. [`sqrt`](/documentation/simd/sqrt) Returns the square root of each element in a vector. [`tgamma`](/documentation/simd/tgamma) Returns the gamma function for each element in a vector. ### Trigonometric Functions [`acos(_:)`](/documentation/simd/acos(_:)-1hgv5) Returns the arccosine of each element in a vector. [`asin(_:)`](/documentation/simd/asin(_:)-72orw) Returns the arcsine of each element in a vector. [`atan(_:)`](/documentation/simd/atan(_:)-9onaa) Returns the arctangent of each element in a vector. [`atan2(_:_:)`](/documentation/simd/atan2(_:_:)-6ogu4) Returns the arctangent of each pair of corresponding elements in two vectors. [`cos(_:)`](/documentation/simd/cos(_:)-3p9ym) Returns the cosine of each element in a vector. [`cospi(_:)`](/documentation/simd/cospi(_:)-57353) Returns the cosine of each element in a vector multiplied by pi. [`sin(_:)`](/documentation/simd/sin(_:)-3p88b) Returns the sine of each element in a vector. [`sinpi(_:)`](/documentation/simd/sinpi(_:)-4lgpo) Returns the sine of each element in a vector multiplied by pi. [`sincos(_:)`](/documentation/simd/sincos(_:)-9pa2l) Returns the sine and cosine of each element in a vector. [`sincospi(_:)`](/documentation/simd/sincospi(_:)-3fwbj) Returns the sine and cosine of each element in a vector multiplied by pi. [`tan(_:)`](/documentation/simd/tan(_:)-5czlf) Returns the tangent of each element in a vector. [`tanpi(_:)`](/documentation/simd/tanpi(_:)-9z76) Returns the tangent of each element in a vector multiplied by pi. [`acos`](/documentation/simd/acos) Returns the arccosine of each element in a vector. [`asin`](/documentation/simd/asin) Returns the arcsine of each element in a vector. [`atan`](/documentation/simd/atan) Returns the arctangent of each element in a vector. [`atan2`](/documentation/simd/atan2) Returns the arctangent of each pair of corresponding elements in two vectors. [`cos`](/documentation/simd/cos) Returns the cosine of each element in a vector. [`cospi`](/documentation/simd/cospi) Returns the cosine of each element in a vector multiplied by pi. [`sin`](/documentation/simd/sin) Returns the sine of each element in a vector. [`sinpi`](/documentation/simd/sinpi) Returns the sine of each element in a vector multiplied by pi. [`tan`](/documentation/simd/tan) Returns the tangent of each element in a vector. [`tanpi`](/documentation/simd/tanpi) Returns the tangent of each element in a vector multiplied by pi. ### Classification Functions [`isfinite(_:)`](/documentation/simd/isfinite(_:)-7d8q7) Returns true for each element that is finite in a vector. [`isinf(_:)`](/documentation/simd/isinf(_:)-4wflm) Returns true for each element that is infinite in a vector. [`isnan(_:)`](/documentation/simd/isnan(_:)-9irpc) Returns true for each element that is not a number (NaN) in a vector. [`isnormal(_:)`](/documentation/simd/isnormal(_:)-61nr1) Returns true for each element that is normal in a vector. ### Alternative Type Alias [`vector_double2`](/documentation/simd/vector_double2) [`double2`](/documentation/simd/double2) --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)