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#1
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Array Formula for a Finite Series Sum ??
Hello;
1) I need to calculate M43:: sum[m=1 to m=9] G(m)*sin(m*x) for a value of "x" tabulated in column L. The 9 values of "m" are tabulated in $D$21:$D$29 The 9 values of G(m) are tabulated in $C$21:$C$29 The first x value is in cell L43 Can someone please help in deriving the array formula to be entered in M43 ?? For other values of x in L44, L45, ... one would simply copy M43 and paste in M44, M45, ... 2) The following formula "obviously" doesn't work: M43::{=SUMPRODUCT($C$21:$C$29,SIN(PRODUCT($D$21:$D $29,L43)))} 3) If it's not too much trouble, how about: N43:: -sum[m=1 to m=9] G(m)*cos(m*x)/m for each value of tabulated x Your help would be greatly appreciated. Regards |
#2
Posted to microsoft.public.excel.worksheet.functions
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Array Formula for a Finite Series Sum ??
Hi,
I have no idea what this is supposed to do but 1. You don't need array entry, 2. PRODUCT serves no purpose, so try: =SUMPRODUCT($C$21:$C$29,SIN($D$21:$D$29*L43)) I get an answer, but of course I made up some of the numbers Also, before you go too far on this one there is a SERIESSUM function in Excel which you might want to look at. The Analysis ToolPak must be attached to use it - Tools, Add-ins, and check it. If this helps, please click yes. "monir" wrote: Hello; 1) I need to calculate M43:: sum[m=1 to m=9] G(m)*sin(m*x) for a value of "x" tabulated in column L. The 9 values of "m" are tabulated in $D$21:$D$29 The 9 values of G(m) are tabulated in $C$21:$C$29 The first x value is in cell L43 Can someone please help in deriving the array formula to be entered in M43 ?? For other values of x in L44, L45, ... one would simply copy M43 and paste in M44, M45, ... 2) The following formula "obviously" doesn't work: M43::{=SUMPRODUCT($C$21:$C$29,SIN(PRODUCT($D$21:$D $29,L43)))} 3) If it's not too much trouble, how about: N43:: -sum[m=1 to m=9] G(m)*cos(m*x)/m for each value of tabulated x Your help would be greatly appreciated. Regards |
#3
Posted to microsoft.public.excel.worksheet.functions
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Array Formula for a Finite Series Sum ??
Hi Shane;
Perfect !! 1) Your formula: =SUMPRODUCT($C$21:$C$29,SIN($D$21:$D$29*L43)) 2) Here're an example: L43::1.8234766 C21::-3.29564E-02 C22::4.57676E-03 C23::-2.65454E-04 C24::1.01688E-04 C25::5.23952E-05 C26::1.12230E-05 C27::-5.97725E-07 C28::8.62970E-06 C29::3.98340E-06 D21::1 D22::2 D23::3 D24::4 D25::5 D26::6 D27::7 D28::8 D29::9 3) Your formula returns:: -0.0338 369 70 and the correct answer is:: -0.0338 369 70 Thank you kindly for your help. "Shane Devenshire" wrote: Hi, I have no idea what this is supposed to do but 1. You don't need array entry, 2. PRODUCT serves no purpose, so try: =SUMPRODUCT($C$21:$C$29,SIN($D$21:$D$29*L43)) I get an answer, but of course I made up some of the numbers Also, before you go too far on this one there is a SERIESSUM function in Excel which you might want to look at. The Analysis ToolPak must be attached to use it - Tools, Add-ins, and check it. If this helps, please click yes. "monir" wrote: Hello; 1) I need to calculate M43:: sum[m=1 to m=9] G(m)*sin(m*x) for a value of "x" tabulated in column L. The 9 values of "m" are tabulated in $D$21:$D$29 The 9 values of G(m) are tabulated in $C$21:$C$29 The first x value is in cell L43 Can someone please help in deriving the array formula to be entered in M43 ?? For other values of x in L44, L45, ... one would simply copy M43 and paste in M44, M45, ... 2) The following formula "obviously" doesn't work: M43::{=SUMPRODUCT($C$21:$C$29,SIN(PRODUCT($D$21:$D $29,L43)))} 3) If it's not too much trouble, how about: N43:: -sum[m=1 to m=9] G(m)*cos(m*x)/m for each value of tabulated x Your help would be greatly appreciated. Regards |
#4
Posted to microsoft.public.excel.worksheet.functions
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Array Formula for a Finite Series Sum ??
Hi,
Glad to help. Cheers, Shane Devenshire "monir" wrote: Hi Shane; Perfect !! 1) Your formula: =SUMPRODUCT($C$21:$C$29,SIN($D$21:$D$29*L43)) 2) Here're an example: L43::1.8234766 C21::-3.29564E-02 C22::4.57676E-03 C23::-2.65454E-04 C24::1.01688E-04 C25::5.23952E-05 C26::1.12230E-05 C27::-5.97725E-07 C28::8.62970E-06 C29::3.98340E-06 D21::1 D22::2 D23::3 D24::4 D25::5 D26::6 D27::7 D28::8 D29::9 3) Your formula returns:: -0.0338 369 70 and the correct answer is:: -0.0338 369 70 Thank you kindly for your help. "Shane Devenshire" wrote: Hi, I have no idea what this is supposed to do but 1. You don't need array entry, 2. PRODUCT serves no purpose, so try: =SUMPRODUCT($C$21:$C$29,SIN($D$21:$D$29*L43)) I get an answer, but of course I made up some of the numbers Also, before you go too far on this one there is a SERIESSUM function in Excel which you might want to look at. The Analysis ToolPak must be attached to use it - Tools, Add-ins, and check it. If this helps, please click yes. "monir" wrote: Hello; 1) I need to calculate M43:: sum[m=1 to m=9] G(m)*sin(m*x) for a value of "x" tabulated in column L. The 9 values of "m" are tabulated in $D$21:$D$29 The 9 values of G(m) are tabulated in $C$21:$C$29 The first x value is in cell L43 Can someone please help in deriving the array formula to be entered in M43 ?? For other values of x in L44, L45, ... one would simply copy M43 and paste in M44, M45, ... 2) The following formula "obviously" doesn't work: M43::{=SUMPRODUCT($C$21:$C$29,SIN(PRODUCT($D$21:$D $29,L43)))} 3) If it's not too much trouble, how about: N43:: -sum[m=1 to m=9] G(m)*cos(m*x)/m for each value of tabulated x Your help would be greatly appreciated. Regards |
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