Different behavior of ./ and .* with vectors [SOLVED] - Printable Version +- HP Forums ( https://www.hpmuseum.org/forum)+-- Forum: HP Calculators (and very old HP Computers) ( /forum-3.html)+--- Forum: HP Prime ( /forum-5.html)+--- Thread: Different behavior of ./ and .* with vectors [SOLVED] ( /thread-8268.html) |

Different behavior of ./ and .* with vectors [SOLVED] - JMB - 04-29-2017 04:22 PM
When both operands of .* or ./ are vectors of the same dimensions, both functions work accordingly: [2,4] .* [2,4] → [4,16] [2,4] ./ [2,4] → [1,1] But when the first operand is a number they behave in a different way: 4 .* [2,4] → [8,16] 4 ./ [2,4] → Error: Invalid dimension In this case the operator * (without the dot), also works: 4 * [2,4] → [8,16] As a workaround for 4 ./ [2,4] one can use: 4 .* [2,4] .^ (-1) → [2,1] 4 * [2,4] .^ (-1) → [2,1] Is this the intended behavior, or should 4 ./ [2,4] also return [2,1] ? RE: Different behavior of ./ and .* with vectors - Tim Wessman - 05-01-2017 04:19 PM
Thanks, we'll put it on the list to investigate. RE: Different behavior of ./ and .* with vectors - JMB - 05-01-2017 05:34 PM
Thank you for your time, Tim! I have noticed now that 4 ./ [2,4] returns the expected result [2,1] in CAS mode. RE: Different behavior of ./ and .* with vectors - compsystems - 05-02-2017 09:11 PM
the Hadamard operations (Hadamard Product .*, Hadamard Power .^, Hadamard Inverse .^-1 and Division ./ ) are Element by Element https://en.wikipedia.org/wiki/Hadamard_product_(matrices) the two arguments must be an array although the math kernel can expand functionality with scalars array vs matrix(linear algebra) operations https://www.mathworks.com/help/matlab/matlab_prog/array-vs-matrix-operations.html HP50 & HPPRIME CAS MODE hadamard([[1,2],[3,4]],[[3,4],[5,6]]) RETURNS [[3,8],[15,24]] // OK HP50 hadamard([1,2],[3,4]) RETURNS [3,8] // ok hadamard([[1,2]],[[3,4]]) RETURNS [[3,8]] // ok HPPRIME CAS MODE hadamard([1,2],[3,4]) RETURNS 5*√5 WHY? hadamard([[1,2]],[[3,4]]) RETURNS [[3,8]] [1,2] .* [3,4] RETURNS [3,8] 4 ./ [2,4] -> [2,1] [4] ./ [2,4] -> [2] /!\ Resize to a smaller size [2,4] ./ [4] -> [1/2] 4 .* ([2,4] .^ -1) -> [2,1] 4./[2,4] -> 4.0 / [2,4] -> 4./[2,4] ? Without spaces also should operate to each element, as some point operations are equivalent to natural operators like [+] [-] [/] RE: Different behavior of ./ and .* with vectors - JMB - 02-02-2018 08:44 PM
Corrected in firmware 13333. Thanks to the HP Prime Team! |