Stephane pointed out on the issue : after calculation and prior to the Acos one, some values were "1.0000000000000002220446" leading to "acos = 2.107D-08i" ; in addition he suggested me to use something like "acos(max(-1,min(1,-1.0000000000000002220446)))" or "acos(max(-1,min(1,1.0000000000000002220446)))" ... very smart :)
Thanks Paul EXPORT CONTROL : Cet email ne contient pas de données techniques This email does not contain technical data De : users [mailto:[email protected]] De la part de Stéphane Mottelet Envoyé : mardi 29 janvier 2019 16:59 À : [email protected] Objet : Re: [Scilab-users] [EXTERNAL] Re: acos leads to complex values It is the same if x is slightly > 1: --> x=1+%eps x = 1. --> acos(x) ans = 2.107D-08i --> format(25); x x = 1.0000000000000002220446 Le 29/01/2019 à 16:55, Carrico, Paul a écrit : When I scroll to the list, the lowest (positive) value is 8.4E-08 (works fine) and no %eps . How Can I check if %eps is in? De : users [mailto:[email protected]] De la part de Stéphane Mottelet Envoyé : mardi 29 janvier 2019 16:50 À : [email protected]<mailto:[email protected]> Objet : [EXTERNAL] Re: [Scilab-users] acos leads to complex values Le 29/01/2019 à 16:45, Carrico, Paul a écrit : Dear All I spent some time in looking for a mistake in my code ; finally I've found that the ACOS of a real vector leads to some complex values (???) acos(Scar_P(:,1) ./ CM_x_CN(:,1)) Are your really sure, because we may have --> x=-1-%eps x = -1. --> acos(x) ans = 3.1415927 - 2.107D-08i S. (the formula worked so far) I checked that the input values are correct: - Comprised between [-1; 1] using MIN and MAX - Composed only of real values using ISREAL (all the vectors are correct) Thus I do not understand why complex values appear ? May it come from the vectorization ? Paul _______________________________________________ users mailing list [email protected]<mailto:[email protected]> https://antispam.utc.fr/proxy/1/c3RlcGhhbmUubW90dGVsZXRAdXRjLmZy/lists.scilab.org/mailman/listinfo/users<https://urldefense.proofpoint.com/v2/url?u=https-3A__antispam.utc.fr_proxy_2_c3RlcGhhbmUubW90dGVsZXRAdXRjLmZy_urldefense.proofpoint.com_v2_url-3Fu-3Dhttps-2D3A-5F-5Fantispam.utc.fr-5Fproxy-5F1-5Fc3RlcGhhbmUubW90dGVsZXRAdXRjLmZy-5Flists.scilab.org-5Fmailman-5Flistinfo-5Fusers-26d-3DDwMG-2Dg-26c-3D0hKVUfnuoBozYN8UvxPA-2Dw-26r-3D4TCz-2D-2D8bXfJhZZvIxJAemAJyz7Vfx78XvgYu3LN7eLo-26m-3DrN8DsnGalih7CBHModSb9evOi3rmZRFFYcBFHTC71gU-26s-3DRgKyyESZ7uSTxlU7V0nR42XTJybjC0Ar5fDcrouQThE-26e-3D&d=DwMG-g&c=0hKVUfnuoBozYN8UvxPA-w&r=4TCz--8bXfJhZZvIxJAemAJyz7Vfx78XvgYu3LN7eLo&m=gwQYJePMwf66Qkf2heyo1UqhkxA31D8XuF0dNsmnvOg&s=WFlVbPNytDi1qDLq35P7qeSGnwD6PCRMRL4tKAtS9no&e=> -- Stéphane Mottelet Ingénieur de recherche EA 4297 Transformations Intégrées de la Matière Renouvelable Département Génie des Procédés Industriels Sorbonne Universités - Université de Technologie de Compiègne CS 60319, 60203 Compiègne cedex Tel : +33(0)344234688 http://www.utc.fr/~mottelet<https://urldefense.proofpoint.com/v2/url?u=https-3A__antispam.utc.fr_proxy_2_c3RlcGhhbmUubW90dGVsZXRAdXRjLmZy_urldefense.proofpoint.com_v2_url-3Fu-3Dhttp-2D3A-5F-5Fwww.utc.fr-5F-2D7Emottelet-26d-3DDwMG-2Dg-26c-3D0hKVUfnuoBozYN8UvxPA-2Dw-26r-3D4TCz-2D-2D8bXfJhZZvIxJAemAJyz7Vfx78XvgYu3LN7eLo-26m-3DrN8DsnGalih7CBHModSb9evOi3rmZRFFYcBFHTC71gU-26s-3D34gC0H3RYWxwcKp7fr4bR5XFfy1acxO72YI9AYJJFhA-26e-3D&d=DwMG-g&c=0hKVUfnuoBozYN8UvxPA-w&r=4TCz--8bXfJhZZvIxJAemAJyz7Vfx78XvgYu3LN7eLo&m=gwQYJePMwf66Qkf2heyo1UqhkxA31D8XuF0dNsmnvOg&s=Z35_aByfKODglW8yDddkINmGp0XVNG2FnCHehVQ_xic&e=> _______________________________________________ users mailing list [email protected]<mailto:[email protected]> https://antispam.utc.fr/proxy/1/c3RlcGhhbmUubW90dGVsZXRAdXRjLmZy/lists.scilab.org/mailman/listinfo/users<https://urldefense.proofpoint.com/v2/url?u=https-3A__antispam.utc.fr_proxy_1_c3RlcGhhbmUubW90dGVsZXRAdXRjLmZy_lists.scilab.org_mailman_listinfo_users&d=DwMG-g&c=0hKVUfnuoBozYN8UvxPA-w&r=4TCz--8bXfJhZZvIxJAemAJyz7Vfx78XvgYu3LN7eLo&m=gwQYJePMwf66Qkf2heyo1UqhkxA31D8XuF0dNsmnvOg&s=DUbP9Ae1PnplwVsabbz8k-6A-ZRz3dLu7e5o5GI9yqU&e=> -- Stéphane Mottelet Ingénieur de recherche EA 4297 Transformations Intégrées de la Matière Renouvelable Département Génie des Procédés Industriels Sorbonne Universités - Université de Technologie de Compiègne CS 60319, 60203 Compiègne cedex Tel : +33(0)344234688 http://www.utc.fr/~mottelet<https://urldefense.proofpoint.com/v2/url?u=http-3A__www.utc.fr_-7Emottelet&d=DwMG-g&c=0hKVUfnuoBozYN8UvxPA-w&r=4TCz--8bXfJhZZvIxJAemAJyz7Vfx78XvgYu3LN7eLo&m=gwQYJePMwf66Qkf2heyo1UqhkxA31D8XuF0dNsmnvOg&s=gdmVN-2pjNdKfA0yL_jVwCc5aMSV0eTSd7Qdt4ClIBo&e=>
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