按照S3官方Wiki的陈述，推荐使用Ubuntu 16.04作为Host端系统，笔者是一名乐于并热衷于尝鲜的搬砖工，于是，尝试在最新的18.04上进行编译和构建S3平台的Linux开发包。以下是操作的完整过程，并不顺利，但以成功告终。
安装Ubuntu 18.04操作系统 ，安装下面的软件包：
sudo apt-get install git-core gnupg flex bison gperf build-essential \zip cURL zlib1g-dev gcc-multilib g++-multilib libc6-dev-i386 \lib32ncurses5-dev x11proto-core-dev libx11-dev lib32z-dev ccache \libgl1-mesa-dev libxml2-utils xsltproc unzip u-boot-tools gawk samba
编译buildroot过程中，会出现若干来自于buildroot packages与Ubuntu18.04自带的工具/包冲突的错误，以下buildroot补丁可处理掉这些错误。
Changes not staged for commit:(use “git add/rm
deleted: package/automake/0001-noman.patchdeleted: package/automake/automake.hashmodified: package/automake/automake.mkdeleted: package/e2fsprogs/0001-sem-init-libs.patchdeleted: package/e2fsprogs/0002-MCONFIG.in-handle-CLOCK_GETTIME_LIB.patchdeleted: package/e2fsprogs/e2fsprogs.hashmodified: package/e2fsprogs/e2fsprogs.mk
diff –git a/package/automake/automake.mk b/package/automake/automake.mkindex 84f05dc..928a33f 100644— a/package/automake/automake.mk+++ b/package/automake/automake.mk@@ -4,7 +4,7 @@#################################################################################-AUTOMAKE_VERSION = 1.15+AUTOMAKE_VERSION = 1.16.1AUTOMAKE_SOURCE = automake-$(AUTOMAKE_VERSION).tar.xzAUTOMAKE_SITE = $(BR2_GNU_MIRROR)/automakeAUTOMAKE_LICENSE = GPLv2+
diff –git a/package/e2fsprogs/e2fsprogs.mk b/package/e2fsprogs/e2fsprogs.mkindex b6e79d2..8a4edc8 100644— a/package/e2fsprogs/e2fsprogs.mk+++ b/package/e2fsprogs/e2fsprogs.mk@@ -4,7 +4,7 @@#################################################################################-E2FSPROGS_VERSION = 1.43.3+E2FSPROGS_VERSION = 1.44.1E2FSPROGS_SOURCE = e2fsprogs-$(E2FSPROGS_VERSION).tar.xzE2FSPROGS_SITE = $(BR2_KERNEL_MIRROR)/linux/kernel/people/tytso/e2fsprogs/v$(E2FSPROGS_VERSION)E2FSPROGS_LICENSE = GPLv2, libuuid BSD-3c, libss and libet MIT-like with advertising clause
完成上述修改以后，按照S3 Linux SDK的编译方法进行编译即可。
已知数列an是首项为a 且公比q不等于一1的等比数列 sn是其前n项和 a1 2a7 3a4成等差数列
a1,a7,a4成等差数列 2a7=a1+a4 2a1q^6=a1+a1q^3 2q^6=1+q^3 2q^6-q^3-1=(2q^3+1)(q^3-1)=0 因为公比Q不等于1， 所以，q^3=-1/2, 2S3*（S12-S6) =2a1(1-q^3)/(1-q)*[a1(1-q^12)/(1-q)-a1(1-q^6)/(1-q)] =2a1(1+1/2)/(1-q)*[a1(1-1/16)/(1-q)-a1(1-1/4)/(1-q)] =[a1/(1-q)]^2[3*(15/16-3/4) =[a1/(1-q)]^2*9/16 =[a1*(3/4)/(1-q)]^2 =[a1*(1-1/4)/(1-q)]^2 =[a1*(1-q^6)/(1-q)]^2 =S6^2 2S3,S6,S12-S6等比 A(3n-2) = aq^(3n-3) = a(q^3)^(n-1) = a(-1/4)^(n-1) T(n) = a + 2*a(-1/4) + 3*a(-1/4)^2 + ... + (n-1)*a(-1/4)^(n-2) + n*a(-1/4)^(n-1) (-1/4)T(n) = 1*a(-1/4) + 2*a(-1/4)^2 + 3*a(-1/4)^3 + ... + (n-1)*a(-1/4)^(n-1) + n*a(-1/4)^n T(n) - (-1/4)T(n) = a + a(-1/4) + a(-1/4)^2 + ... + a(-1/4)^(n-1) - n*a(-1/4)^n = a[1 - (-1/4)^n]/[1 - (-1/4)] - n*a(-1/4)^n = 4a[1 - (-1/4)^n]/5 - na(-1/4)^n, T(n) = {4a[1 - (-1/4)^n]/5 - na(-1/4)^n}*[1/(1+1/4)] = {4a[1 - (-1/4)^n]/5 - na(-1/4)^n}*4/5 = 16a[1 - (-1/4)^n]/25 - 4na(-1/4)^n/5
如图所示电路图R1=2欧，R2=3欧。当开关S1闭合，S2，S3断开时,电流表的示数为0.6A,当开关S1.S2.S3都闭合时
1、当开关S1闭合，S2，S3断开时,电流表的示数为0.6A，这时R1R2串联。 总电阻R=R1+R2=2Ω+3Ω=5Ω电源电压U=IR=0.6A*5Ω=3V2、当S1 .S2. S3.都闭合时，R1被短路，R2和灯泡并联，电流表测量总电流示数为I=1.5A，且灯泡正常发光，所以灯泡额定电压U额=3V,这时I2=U/R2=3V/3Ω=1A,I灯=I-I2=1.5A=1A=0.5A灯泡额定功率P额=U额I=3V*0.5A=1.5w3、当S1 .S2. S3.都闭合时，通电1min，电流通过电阻R2所做的功。 W2=UI2t=3V*1A*60s=180J
如图，在Rt△ABC中，∠C=90°，AC=4，BC=2，分别以AC、BC为直径画半圆，则图中阴影部分的面积为
S阴影=S半圆1+S半圆2-S△ABC=1/2×2×2×π+1/2×1×1×π-1/2×4×2=5/2π-4≈3.85
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