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  • 中国面包师贴吧-楼主(阅:3288/回:0)用正割对数计算微积分的方法2

    第三部分古今算学丛书假数测圆

    推导过程可参见《古今算学丛书,割圆密率捷法》,清光绪戊戌六月算学书局印成,1898年刘铎整理,

    圆周率π=3.141592653589793238462643186367472279514(小于71519),

    推导过程参见《古今算学丛书,假数测圆》清光绪戊戌六月算学书局印成,清咸丰壬子年,湖北人戴煦识,夏鸾翔编写,1898年刘铎整理,

    以本弧弧分径,求四十五度以内正割对数。

    术曰:先求各率分子,为递次乘法,以二为数根,即为第一乘法,置前数根,加二得四,为数根,置前乘法,四五递乘之,一二递除之,得二十,为初减数,以数根减初减数,得十六,为第二乘法,置前数根,加二,得六,为数根,置前初减数,六七递乘之,三四递除之,得七十,为初减数,置前乘法六七,递乘之,一二递除之,得三百三十六,为次减数,以数根减初减数,得六十四,再减次减数,得二百七十二为第三乘法,置前数根加二,得八,为数根,置前初减八九递乘之,五六递除之,得一百六十八,为初减数,置前次减八九递乘之,三四递除之,得二千零十六,为次减数,置前乘法八九递乘之,一二递除之,得九千七百九十二,为三减数,以数根减初减,得一百六十,再减次减,得一千八百五十六,再减三,减得七千九百三十六,为第四乘法,凡数根均起各偶数,其求各减数,则用偶奇二数,乘而逐次,乘法递加,如第二乘法,用四五乘,第三乘法用六七乘,再用奇偶二数,除而,挨次减数递降,如第三乘法,初减用三四除,次减用一二除,乘法将一位,则多一减,如是递求得各率分子,即为递次乘法。

    根据以上描述,推导出

    第一乘法    二           2                                 S   =2

                                                                 1  

                            2*4*5          

    第二乘法    一六                   -2*2=16                      S   =16      

                             1*2                                 2        

                              20

                           16*6*7    20*6*7    

    第三乘法    二七二                 -         +2*3=272            S   =272      

                             1*2       3*4                         3    

                             336       70    

                           272*8*9   336*8*9  70*8*9  

    第四乘法    七九三六               -        +         -2*4=7936   S   =272      

                             1*2       3*4     5*6                  4    

                            9792      2016     168

                       7936*10*11  9792*10*11  2016*10*11  168*10*11

    第五乘法  三五三七九二           -            +           -         +2*5= 353792    

                          1*2         3*4         5*6        7*8                

                         436480      89760        7392       330      10

                                                                  S    =353792

                                                                    5

    第六乘法  三五三七九二

    353792*12*13   436480*12*13   89760*12*13    7392*12*13   330*12*13

                 -              +               -           +          -2*6=22368256  

    1*2            3*4             5*6            7*8        9*10        

    27595776       5674240        466752         20592       572      12

                                                                  S  = 22368256

                                                                    6

    第七乘法     一九零三七五七三零零

    第八乘法     二零九八六五三零零零零零

    第九乘法     二九零八八八九零零零零零零零

    第十乘法     四九五一五零零零零零零零零零零零

    第十一乘法   一零一五四二零零零零零零零零零零零零零

    第十二乘法   一零一五四二零零零零零零零零零零零零零

    第十三乘法   七零二五二零零零零零零零零零零零零零零零零零零

    第十四乘法   二三一二零零零零零零零零零零零零零零零零零零零零零零

    把上面的计算过程,用数学归纳法,得到下面的公式

                         S   *(2n-2)(2n-1)             S  *(2n-4)(2n-3)

                           n-2                         n-3              

           S   *2n(2n+1)                 *2n(2n+1)                   *2n(2n+1)            

            n-1                1*2                        1*2

    S    =             -                          +                          …-2              

    n        1*2                3*4                         5*6

    对数的计算, lg0.98=(1-0.98)*0.434294482,

    a     对数根     0.434294482                                     a=0.434294482

    b     第一数     (1-0.98)*0.434294482=0.00868588964                b=(1-N)*a

    c     第二数      0.00868588964*0.02/2=0.00008685890               c=b(1-N)/2

    d     第三数      0.00008685890*0.02*2/3=0.00000115812             d=c*(1-N)*2/3

    e     第四数      0.00000115812*0.02*3/4=0.00000001737             e=d*.(1-N)*3/4

    f      九率        0.000000017378*0.02*4/5=0.00000000028           f=e*(1-N)*4/5

    lg0.98=-0.00868588964-0.00008685890-0.00000115812-0.00000001737-0.00000000028=-0.00877392431,

    lg98=2-lg0.98=2-0.00877392431=1.99122607569,

    当N<1时

                              2     3              4                5        

                         (1-N)   (1-N)    2     (1-N)   2     3    (1-N)   2    3   4

    lgN=0.434294482[(1-N)+      +            +                  +                  

                           2      2     3       2    3     4      2    3    4    5    

             n      

         (1-N)    2     5     4       n-1

    +…+                          …       ]

          2      3     4     5        n

                      m              

    当N>1时,且N/10    <1,

                            m  2        m  3               m  n  

                      (1-N/10  )   (1-N/10  )     2      (1-N/10  )   2    3    4   n-1

    lgN=0.434294482[m-[           +                 +..+                        …  ]]  

                           2          2        3          2       3    4    5    n

    因为,    可参见高等教育出版社菲赫金哥尔茨著1953年版《微积分教程》第二卷第二分册,

    398.对数的计算,

          lgn

    ln n=

           lge

    所以,

            lgsecθ

    lnsecθ=      

    lge

    e=2.71828182846, lge=0.4342944819,

            lgN

    lnN=      

    0.4342944819

    当N<1时

                              2     3              4                5        

                         (1-N)   (1-N)    2     (1-N)   2     3    (1-N)   2    3   4

    lnN= (1-N)+      +            +                  +                  

                           2      2     3       2    3     4      2    3    4    5    

             n      

         (1-N)    2     5     4       n-1

    +…+                          …       ]

          2      3     4     5        n

                      m              

    当N>1时,且N/10    <1,

                            m  2        m  3               m  n  

                      (1-N/10  )   (1-N/10  )     2      (1-N/10  )   2    3    4   n-1

    lnN=m-[           +                 +..+                        …    ]  

                           2          2        3          2       3    4    5    n

    正割对数的计算公式

    法检弧线表,得四十五度,弧分单位下,七八五三九八一六三四零为二率,自乘,得单位下六一六八五零二七五零七二,为三率,以对数根,单位下四三四二九四四八一九零三乘之,二除之,得零一三三九四七三三五三一,为第一数正,次置第一数,以三率乘之,得五率,三除之,四除之,得连单位三零下六八八五四五四二一九二六,为七率,用数第一乘法,二乘之,得一三七七零九零八四四,为第二数正,次置七率,用数以三率乘之,得七七六三八,为九率,用数第二乘法,一六乘之,得二二六五二二三六四,为第三数正,次置九率,用数以三率乘之,得九率,七除之,八除之,得连单位六零下一五五九四九零八七八二,为十一率,用数第三乘法二七二乘之,得四二四一八一五二,为第四数正,次置十一率,用数以三率乘之,得十一率,九除之,十除之,得连单位八零下一零六八八五八一九七,为十三率,用数第四乘法七九三六乘之,得八四八二四五九,为第五数正,次置十三率,用数以三率乘之,得十三率,十一除之,十二除之,得连单位十一零下四九九四八八九九五,为十五率,用数第五乘法三五三七九二乘之,得一七六七一五二,为第六数正,次置十五率,用数以三率乘之,得十五率十三除之,十四除之,得连单位十三零下一六九二九一一七,为十七率,用数第六乘法二二三六八二五六乘之,得三七八六七五,为第七数正。次置十七率,用数以三率乘之,得十七率,十五除之,十六除之,得连单位十六零下四三五一一三七七,为十九率,用数第七乘法一九零三七五七三下连单位二零乘之,得八二八三五,为第八数正,次置十九率用数以三率乘之,得十九率,十七除之,十八除之,得连单位十九零下八七七一二四三,为二十一率,用数第八乘法二零九八六五三下,连单位五零乘之,得一八四零八,为第九数正,次置二十一率,用数以三率乘之,得一八四零八,为第九数正,次置二十一率,用数以三率乘之,得二十一率,十九除之,二十除之,得连单位二十一零下一四二三八二七,为二十三率,用数第九乘法二九零八八八九下,连单位七零乘之,得四一四二,为第十数正,次置二十三率,用数以三率乘之,得二十三率,二十一除之,二十二除之,得连单位二十四零下一九零一零五,为二十五率,用数第十乘法四九五一五零下,连单位十零,乘之,得九四一,为第十一数正,次置二十五率,用数以三率乘之,得二十五率,二十三除之,二十四除之,得连单位二十七零下二一二四四,为二十七率,用数第十一乘法一零一五四二下,连单位十三零乘之,得二一六,为第十二数正,次置二十七率,用数以三率乘之,得二十七率,二十五除之二十六,除之,得连单位三十零下二零一六零,为二十九率,用数第十二乘法二四六九二下连单位十六零,乘之,得五零,为第十三数正,次置二十九率,用数以三率乘之,得二十九率,二十七除之,二十八除之,得连单位三十三零下一六四五,为三十一率,用数第十三乘法,七零二五二下连单位十八零乘之,得一十二,为十四数正,次置三十一率,用数以三率乘之,得三十一率,二十九除之,三十除之,得连单位三十六零下一一七第十四,乘法二三一二下连单位二十一零乘之,得三,为第十五数正,乃以诸正数相并,得零一五零五一四九九七八四,以半径一百亿系十一位乃于首位加一零,尾位未满五弃之,得一零一五零五一四九九七八,为四十五度正割对数也。

    余切对数求法

    lgsec44°+10=10.1430659099,

    lgsec44°+20=20.1430659099,

    lgcsc44°+10=10.1582287268,

    lgtg44°=lgsec44°+20-lgcsc44°-10-10=20.1430659099-10.1582287268-10=9.9848371831-10=-0.015162817,

    lgctg44°=lgcsc44°+20-lgsec44°-10-10=20.1582287268-10.1430659099-10=0.01516282,

    lgctgθ=lgcscθ-lgsecθ,

    lgctg44°=lgcsc44°-lgsec44°=-0.1431+0.1582=0.0151,

    lgtgθ=lgsecθ-lgcscθ,

    lgctgθ=lgcscθ-lgsecθ,

    lntgθ=lnsecθ-lncscθ,

    lnctgθ=lncscθ-lnsecθ,

    正弦对数求法

    lgcsc44°+10=10.1582287269,

    lgsin44°=20-lgcsc44°-10-10=9.8417712731-10=-0.158287269,

    lgsinθ=-lgcscθ,

    lgcosθ=-lgsecθ,

    lnsinθ=-lncscθ,

    lncosθ=-lnsecθ,

    正矢对数求法

    44°/2=22°,

    45°-22°=23°,

    lg2+3=3.03010299956,

    2*[(lgcsc22°)/10+1]=2*1.04264245830=2.08528491660,

    lgversin44°=[lg2+3-2*[(lgcsc22°)/10+1]-1]*10=(3.03010299956-2.08528491660-1)*10=(0.94481808296-1)*10=-0.5518190172,

    lgversin44°=lg(1-cos44°)=lg0.28066=-0.551819479,

    lgversinθ=[lg2+3-2*[lgcsc(θ/2)]/10+1]-1]*10,

    2*[(lgcsc23°)/2+1]=1.04081219884*2=2.08162439768,

    lgvercos44°=2*[(lgcsc23°)/2+1]-[lg2+3-2*[(lgcsc22°)/10+1]]*10-10=2.08162439768-9.4481808296-10=9.4847860188-10=-0.515213982,

    lgvercosθ=2*[(lgcsc(90°-θ))/2+1]-[lg2+3-2*[(lgcscθ/2)/10+1]]*10-10,

    正大矢对数求法

    44°/2=22°,

    45°-22°=23°,

    lg2+3=3.03010299956,

    2*[(lgcsc22°)/10+1]=2*1.00328341395=2.00656682790,

    lgvercos23°=10*[lg2+3-2*[(lgcsc22°)/10+1]-10]-1=[3.03010299956-2.00656662790-10]*10-1=1.02353617166*10-1=0.2353617166

    lgvercosθ=10*[lg2+3-2*[(lgcsc(45°-θ)/10)+1]-10]-1

    2*[(lgsec23°)/10+1]=1.00359739173*2=2.00719478346,

    lgvercos22°=lg2+3-2*[(lgcsc23°)/10+1]-10=3.03010299956-2.00719478346-10=1.02290821610

    正割对数计算公式

    对数根0.434294481903,

    a    二率    θ=0.78539816340                                    a=θ

                 2                                                        2  

    b     三率 θ =0.78539816340*0.78539816340=0.616850275072          b=θ

    c  第一数正 0.616850275072*0.434294481903/2=0.13394733531    c=0.434294481903*b/2

    d 七率  0.13394733531*0.616850275072/3*4=0.00688545421926    d=c*b/3*4

    e第二数正   0.00688545421926*2=0.01377090844               e=2d

    f    九率  0.00688545421926*0.616850275072/5*6=0.00014157648  f=bd/5*6

    g第三数正0.00014157648*16=0.00226522364                    g=f*16

    h第十一率0.00014157648*0.616850275072/7*8=0.00000155949     h=bf/7*8

    i第四数正0.00000155949*272=0.0004218153                     i=272h

    j第十三率0.00000155949*0.616850275072/9*10=0.00000001069     j=bh/9*10

    k第五数正0.00000001069*7936=0.00008482454                  k=7936*j

    m第十五率0.00000001069*0.616850275072/11*12=0.0000000000499488995  m=bj/11812

    n第六数正0.0000000000499488995*353792=0.00001767152        n=353792m

    o第十七率0.0000000000499488995*0.616850275072/13*14=169291167E13  o=bm/13*14

    p第七数正169291167E13*22368256=378674816E6                 p=22368256o

    q第十九率169291167E13*0.616850275072/15*16=43511377E15     q=bo/15*16

    s第八数正43511377E15*1903757300=8283E5                    s=1903757300q

    t第二十一率43511377E15*0.616850275072/17*18=877124343196E18   t=bq/17*18

    u第九数正877124343196E18*209865300000=184077963212E6    u=209865300000t

    当45°≥θ>0°时

                          2                 2   2                                                

           0.434294481903θ   0.434294481903θ   θ     2    

    lgsecθ=                +                             +  

                2                  2           1    3*4                  

                          2    2         2                            2   S  

           0.434294481903θ   θ     2    θ     16       0.434294481903θ      n

                                         +...+

                2            1    3*4   1     5*6             2      (n+1)(n+2)...*2n                            

                              2      4            6                8

                             θ     θ     2      θ    2    16     θ     2   16 272

    lgsecθ=0.434294481903(     +           +                 +  

                              2     2   3*4     2    3*4   5*6    2  3*4  5*6  7*8

          10                            2n     S              

        θ     2   16   272  7936      θ          n

    +                           +…+                    )    

         2  3*4  5*6  7*8   9*10       2   (n+1)(n+2)...*2n

    上式中,

                              S     *(2n-2)(2n-1)                S     *(2n-2)(2n-1)          

                                n-2                              n-3

           S    *2n(2n+1)                          *2n(2n+1)                *2n(2n+1)            

             n-1                     1*2        

    S   =                  -                                 +                  …-2              

    n        1*2                          3*4                           5*6        

    lgsec45°=lgsec0.78539816340=0.13394733531+0.01377090844+0.00226522364+0.0004218153+0.00008482454=0.15049010723,

    当67.5°≥θ>45°时

    lgsecθ=lgsec(2θ-90°)-lgsec(90°-θ)+lg2,

      当78.75°>θ≥67.5°时

    lgsecθ=lgsec[2(2θ-90°)-90°]-lgsec2(90°-θ)-lgsec(90°-θ)+2lg2,

    当84.375°>θ≥78.75°时

    lgsecθ=lgsec[2[2(2θ-90°)-90°]-90°]-lgsec4(90°-θ)-lgsec2(90°-θ)-lgsec(90°-θ)+3lg2,

    当85.375°>θ≥84.375°时

    lgsecθ=lgsec[2[2[2(2θ-90°)-90°]-90°]-90°]-lgsec6(90°-θ)-lgsec4(90°-θ)-lgsec2(90°-θ)-lgsec(90°-θ)+4lg2,

    当86.375°>θ≥85.375°时,

    lgsecθ=lgsec[2[2[2[2(2θ-90°)-90°]-90°]-90°]-90°]-lgsec8(90°-θ)-lgsec6(90°-θ)-lgsec4(90°-θ)-lgsec2(90°-θ)-lgsec(90°-θ)+5lg2,

    当87.375°>θ≥86.375°时,

    lgsecθ=lgsec[2[2[2[2[2(2θ-90°)-90°]-90°]-90°]-90°]-90°]-lgsec8(90°-θ)-lgsec8(90°-θ)-lgsec6(90°-θ)-lgsec4(90°-θ)-lgsec2(90°-θ)-lgsec(90°-θ)+6lg2,

    当88.375°>θ≥87.375°时,

    lgsecθ=lgsec[2[2[2[2[2[2(2θ-90°)-90°]-90°]-90°]-90°]-90°]-90°]-lgsec12(90°-θ)-lgsec10(90°-θ)-lgsec8(90°-θ)-lgsec6(90°-θ)-lgsec4(90°-θ)-lgsec2(90°-θ)-lgsec(90°-θ)+7lg2,

    因为, 可参见高等教育出版社菲赫金哥尔茨著1953年版《微积分教程》第二卷第二分册,

    398.对数的计算,

         lgn      

    ln n=

          lge

    所以,

            lgsecθ      

    lnsecθ=

              lge

    e=2.71828182846, lge=0.4342944819,

                lgsecθ      

    lnsecθ=

             0.4342944819

    所以,当45°≥θ>0°时

              2       4              6                   8    

            θ       θ      2       θ     2      16     θ      2    16     272

    lnsecθ=       +            +                     +  

            2        2    3*4      2    3*4     5*6     2    3*4   5*6    7*8

              10                                  2n       S      

            θ      2    16    272   7936        θ             n  

    +                                 +…+              

            2      3*4  5*6   7*8   9*10        2      (n+1)(n+2)...*2n

    上式中,

                              S     *(2n-2)(2n-1)                S     *(2n-2)(2n-1)          

                                n-2                              n-3

           S    *2n(2n+1)                          *2n(2n+1)                *2n(2n+1)            

             n-1                     1*2        

    S   =                  -                                 +                  …-2              

    n        1*2                          3*4                           5*6    

    当67.5°≥θ>45°时

    lnsecθ=lnsec(2θ-90°)-lnsec(90°-θ)+ln2,

      当78.75°>θ≥67.5°时

    lnsecθ=lnsec[2(2θ-90°)-90°]-lnsec2(90°-θ)-lnsec(90°-θ)+2ln2,

    当84.375°>θ≥78.75°时

    lnsecθ=lnsec[2[2(2θ-90°)-90°]-90°]-lnsec4(90°-θ)-lnsec2(90°-θ)-lnsec(90°-θ)+3ln2,

    当85.375°>θ≥84.375°时

    lnsecθ=lnsec[2[2[2(2θ-90°)-90°]-90°]-90°]-lnsec6(90°-θ)-lnsec4(90°-θ)-lnsec2(90°-θ)-lnsec(90°-θ)+4ln2,

    当86.375°>θ≥85.375°时,

    lnsecθ=lnsec[2[2[2[2(2θ-90°)-90°]-90°]-90°]-90°]-lnsec8(90°-θ)-lnsec6(90°-θ)-lnsec4(90°-θ)-lnsec2(90°-θ)-lnsec(90°-θ)+5ln2,

    当87.375°>θ≥86.375°时,

    lnsecθ=lnsec[2[2[2[2[2(2θ-90°)-90°]-90°]-90°]-90°]-90°]-lnsec8(90°-θ)-lnsec8(90°-θ)-lnsec6(90°-θ)-lnsec4(90°-θ)-lnsec2(90°-θ)-lnsec(90°-θ)+6ln2,

    当88.375°>θ≥87.375°时,

    lnsecθ=lnsec[2[2[2[2[2[2(2θ-90°)-90°]-90°]-90°]-90°]-90°]-90°]-lnsec12(90°-θ)-lnsec10(90°-θ)-lnsec8(90°-θ)-lnsec6(90°-θ)-lnsec4(90°-θ)-lnsec2(90°-θ)-lnsec(90°-θ)+7ln2,

    例如:

    lgsec2°+10=10.0002646411,

    lgsec2°+20=20.0002646411,

    lgsec44°+10=10.1430659099,

    lg2=0.301029995,

    lgsec44°+10-lg2=10.1430659099-0.301029995=9.842035904,

    lgsec46°=lgsec2°+10+10-lgsec44°-10-lg2-10=20.0002646411-9.842035904-10=10.15822874-10=0.15822874,

    lnsecθ=lnsec(2θ-90°)-lnsec(90°-θ)+lg2,

    例如:

    lgsec4°+10=10.00010592102,

    lgsec4°+20=20.00010592102,

    lgsec43°+10=10.1358725362,

    lg2=0.301029995,

    lgsec43°+10-lg2=10.1358725362-0.301029995=9.8348425406,

    lgsec47°=lgsec4°+10+10-lgsec43°-10+lg2-10=20.00010592102-9.8348425406-10=10.1662166696-10=0.1662166696,

    lnsecθ=lnsec(2θ-90°)-lnsec(90°-θ)+lg2

    0.00011-0.1359+0.301029995

    lnsecθ=lnsec(2θ-90°)-lnsec(90°-θ)+lg2,

    例如:

    lnsec67°=lnsec(2*67°-90°)-lnsec(90°-67°)-lg2

           =lnsec44°-lnsec23°+lg2

    因为,

    lnsinθ=-lncscθ,

    lncosθ=-lnsecθ,

    lnsec67°=-lncos44°+lncos23°+lg2

        =0.1431-0.036+0.301029995=-0.408129995

    例如:

    lgsec68°=lgsec(2*68°-90°)-lg(90°-68°)+lg2

           =lgsec46°-lgsec22°+lg2

    lgsec68°=lgsec(2*46°-90°)-lgsec(90°-46°)+lg2-lgsec22°+lg2

           =lgsec2°-lgsec44°+lg2-lgsec22°+lg2

           =0.30003-0.1431-0.0328+0.301029995

           =0.42519995

    例如:

    lgsec79°=lgsec(2*79°-90°)-lg(90°-79°)+lg2

           =lgsec68°-lgsec11°+lg2

    lgsec68°=lgsec(2*46°-90°)-lgsec(90°-46°)+lg2-lgsec22°+lg2

           =lgsec2°-lgsec44°+lg2-lgsec22°+lg2

           =0.30003-0.1431-0.0328+0.301029995

           =0.42519995

    lgsec79°=lgsec(2*79°-90°)-lg(90°-79°)+lg2

          =lgsec68°-lgsec11°+lg2

          =0.42519995-0.00081+0.301029995

    .      =0.725419495

    例如:

    lgsec85°=lgsec(2*85°-90°)-lg(90°-85°)+lg2

           =lgsec80°-lgsec5°+lg2

    lgsec80°=lgsec(2*80°-90°)-lg(90°-80°)+lg2

            =lgsec70°-lgsec10°+lg2

    lgsec70°=lgsec(2*70°-90°)-lg(90°-70°)+lg2

            =lgsec50°-lgsec20°+lg2

    lgsec50°=lgsec(2*50°-90°)-lg(90°-50°)+lg2

            =lgsec10°-lgsec40°+lg2  

      推导过程可参见《对数表新编》冯度编开明书店出版1935年版

         logcosα计算公式,当88°<α<90°时,

    如果88°≤α<90°,根据《对数表新编》中的S,T公式,判断余弦对数值,

    log cosα=log (90°-α)``+S,

    log cotα=log (90°-α)``+T,

    上式中,

    90°-α=MN°WS`T``,

    (90°-α)``=3600*MN+60*WS+T,

    log (90°-α``)/1000=lgA.BC,

    如果0≤(90°-α``)<7267,

    那么,log cosα=log (90°-α``)/1000+3+4.68553,

                  =lg A.BC+3+4.68553,

    计算log cosα时,首先计算log(90°-α``)/1000,再加上3,最后加上4.68553,这样得到的数后面附加-10,给这个数减去10,就是log sinα的值,

    例如:

    log cos88°26`41.2``=log5598.8+4.68553≈3.74809+4.68553 - 10 ≈8.43362 - 10 ≈-1.56639,

    log cos88°26`41.2``=log5591.87+4.68553≈3.7462+4.68553 - 10 ≈8.43173 - 10 ≈-1.56827,

    0.027145*10000=271.45*20.6=5591.87,

    90°-88°26`41.2``=1°33`18.8``=0.027145,

    第四部分导数的定义

    推导过程可参见1992年版《高等数学》,盛祥耀主编,高等教育出版社出版

    三   导数的几何意义

    根据导数定义及曲线的切线的斜率的求法,我们可以知道,

    函数y=f(x)在点x    处的导数的几何意义就是曲线y=f(x)在点(x   ,f(x    ))处的切线的斜率,如图2-2,即

    tga=f`(x    )

            0

    由此可知曲线y=f(x)上点P   处的切线方程为

                            0

       y-y    =f`(x    )(x-x     )

          0       0       0

    法线方程为

                -1

    y-y    =           (x-x   )(f`(x  )≠0)  

        0     f`(x   )       0    0

                  0        

    积分表        

    kdx=kx+C  

           μ     1     μ-1

    x  dx=        x    +C    (μ≠-1)

                 μ+1                      

    dx/x=ln│x│+C  

            x      x              

          a   dx=a   /lna+C

    当a=e时,

            x      x              

          e   dx=e    +C

          cosxdx=sinx   +C

          sinxdx=-cosx   +C

              2        

          sec   xdx=tgx    +C

              2        

          csc   xdx=-ctgx    +C

          secxtgxdx=secx    +C

          cscxctgxdx=-cscx   +C

            dx          

                   =arcsinx+C=-arccosx     +C

              2

    1-x

            dx          

                   =arctgx+C=-arcctgx   +C

              2

    1-x

          shxdx=chx   +C

           chxdx=shx  +C

            m      m+1        

          x    dx=x     /(m+1)+C

          dx/x=         d(-x)/(-x)=log│x│+c

            x      x      

          a    dx=a    /log a    +c

           cosxdx=sinx   +C

          sinxdx=-cosx  +C

                2          

          dx/cos   x=tan x    +c

                     2       ±arc sinx+c    

          dx/     1-x     ={

                             ±arc cosx+c

                2          

          dx/ (x   +1)  =arc tanx+c

          chxdx=shx+c

          shxdx=chx+c

               2      

          dx/ch   x=thx+c

                   2      

          dx/     x  -1   =±argchx+c

                 2          

           dx/(1-x   )=±argthx+c

    积分计算过程

    根据下面的公式,tga=y`=f`(x)=u(x)=y/x,a=arctgy`,

                3        5                 2n+1

              f`  (x)   f`   (x)          n  f`   (x)       2n+2

    a=f`(x)-        +         -...+(-1)             +o(x      )    

               3        5                2n+1          

                         2        5        6               2m

                        a        a       a           m   a         2m+1

    f(x)=-lncosa+C=-ln[1-       +        -         -...+(-1)          +o(a      )]+C    

                       2!        4!      6!             (2m)!  

                                 1         2   1         3       6

    f(x)=lnseca+C=(sec a-1)-     (sec x-1) +      (sec x-1)  +o(a   )

                                  2            3

                          2        4        6          

                        a        a       a          6

    f(x)=-lncosa+C=       +        +         +o(a      )

                    2        12     45      

    kdx=kx+C  

                          2        4        6          

                        a        a       a          6

    f(x)=-lncosa+C=       +        +         +o(a      )

                    2        12     45      

                3        5               2n+1

               x        x           n   x          2n+2

    arc tg x=x-       +         -...+(-1)          +o(x      )    

           3        5              2n+1        

    a=arctgy`,上式中,

                3        5               2n+1

               k        k           n   k          2n+2

    a=k-       +         -...+(-1)          +o(x      )    

           3        5              2n+1      

                                 3       5               2n+1  

                        1       k      k         n     k             2n+2    

    f(x)=-lncosa+C=       [k-     +       -…+(-1)                +o(a      ) ]

                    2       3      5              2n+1      

                                 3       5               2n+1  

                        1       k      k         n     k             2n+2    

    +       [k-     +       -…+(-1)                +o(a      ) ]

                    12      3      5              2n+1      

                                 3       5               2n+1  

                        1       k      k         n     k             2n+2    

    +       [k-     +       -…+(-1)                +o(a      ) ]

                    45      3      5              2n+1      

               =kx

             2  

    csc   xdx=-ctgx+C=f(x)

                          2        4        6          

                        a        a       a          6

    f(x)=-lncosa+C=       +        +         +o(a      )

                    2        12     45      

                3        5               2n+1

               x        x           n   x          2n+2

    arc tg x=x-       +         -...+(-1)          +o(x      )    

               3        5              2n+1  

       a=arctgy`,上式中,

                   2   3       2  5            2   2n+1

         2     (csx   x)    (csx  x)        n  (csx  x)         2n+2

    a=(csx   x)-         +          -...+(-1)              +o(x      )    

              3         5                 2n+1      

                                    2   3    2   5            2  2n+1  

                    1       2    (csx  x)  (csx  x)       n  (csx  x)           2n+2    

    f(x)=-lncosa+C=       [(csx  x)-        +        -…+(-1)                +o(a      ) ]

               2                3      5               2n+1      

                                     2  3    2  5            2  2n+1  

                    1       2    (csx  x)  (csx  x)       n  (csx  x)           2n+2    

    +      [(csx  x)-        +         -…+(-1)                +o(a      ) ]

               12               3       5               2n+1      

                                     2  3    2  5            2  2n+1  

                    1       2    (csx  x)  (csx  x)       n  (csx  x)           2n+2    

    +      [(csx  x)-        +         -…+(-1)                +o(a      ) ]

               45               3       5               2n+1      

           =-ctgx

    shxdx=chx   +C

                          2        4        6          

                        a        a       a          6

    f(x)=-lncosa+C=       +        +         +o(a      )

                    2        12     45    

       上式中

                   3        5            2   2n+1

                sh   x     sh   x       n     sh   x        2n+2

    a=sh x-           +          -...+(-1)              +o(x      )    

              3         5                 2n+1      

                                3        5               2n+1            

                    1        sh   x    sh  x        n    sh   x          2n+2    

    f(x)=-lncosa+C=       [shx-        +         -…+(-1)                +o(a      ) ]

               2           3        5               2n+1      

                                3        5               2n+1            

                    1        sh   x    sh  x        n    sh   x          2n+2    

    +       [shx-        +         -…+(-1)                +o(a      ) ]

               12           3        5               2n+1    

                                3        5               2n+1            

                    1        sh   x    sh  x        n    sh   x          2n+2    

    +       [shx-        +         -…+(-1)                +o(a      ) ]

               45           3        5               2n+1      

           =chx

    例1.

             3    2        

    (4x   -2x   -5x-3)dx

                  3               2                              

    =4        x   dx-         2x   dx+         5xdx-        3dx        

         4        3        2

         x        x        x  

    =4       -2       +5       -3x+C        

    4        3        2

         3       2      

         2x      5x      

    =x-       +       -3x+C        

    3        3      

             3    2        

    (4x   -2x   -5x-3)dx

                          2        4        6          

                        a        a       a          6

    f(x)=-lncosa+C=       +        +         +o(a      )

                    2        12     45    

    上式中      

                         3    2     3     3   2      5          3    2      2n+1                              

         3     2      (4x  -2x  -5x-3)   (4x  -2x  -5x-3)      n  (4x  -2x  -5x-3)    2n+2    

    a=(4x   -2x  -5x-3)-               +               -…+(-1)                 +o(a  ) ]

                        3              5                      2n+1      

    导数公式表

    (c)`=0,

      a     a-1              

    (x  )`=ax

      x     x          

    (a   )`=a   lna

       x    x      

    (e    )`=e

    (log  x)`=1/xlna

       a

    (lnx)`=1/x

    (sinx)`=cosx

    (cos)`=-sinx

             2    

    (tgx)`=sec   x

             2

    (ctgx)`=-csc   x

    (secx)`=secxtgx,

    (cscx)`=-cscxctgx,

                 1  

    (arcsinx)`=        2

                 1-x

                 -1  

    (arccosx)`=        2

                 1-x

                 1  

    (arctgx)`=        2

                 1+x

                 -1  

    (arcctgx)`=        2

                 1+x

      x      x      x                                

    (a    )`=a   lga =a  /log  e

                          a

    (log   x)`=log  e/x=1/(xlog a)

    a       a

    (lg  x)`=1/x

                          2      

       (arc cosx)`=-ε/    1-x          ε=±1,其号与siny之号同

                          2      

       (arc sinx)`=ε/    1-x          ε=±1,其号与cosy之号同

                   2      

    (arc tanx)`=1/ (1+x   )

    (u+v+w)`=u`+v`+w`   (u,v,w,表x之函数而有引数u`,v`,w`者

    (uvw)`=u`/u+v`/v+w`/w  

                    2    

    (u/v)`=[(vu`-uv`)/v   ]

      v    v          v-1                    

    u   =u   v`log u+vu  u`

    x=φ(y)  [x=φ(y)表y=f(x)之反函数,而y有引数f`(x)=0]

    x`=φ`(y) =1/f`(x)

    [备考]——三角函数cotx=cosx/sinx,secx=1/cosx,cscx=1/sinx,versx=1-cosx,covsx=1-sinx等或为两函数之商,或为两函数之和,

    导数计算过程

    因为,tga=y`=f`(x)=u(x),

                            3              

                       arctg   (y/x)      

    y`=u(x)=t=arctg(y/x)+

                            3

      a              

    (x   )`=ax,

                              3   a            

                   a     arctg   (x   /x)      a-1

    y`=u(x)=t=arctg(x   /x)+                  =ax  

                             3

    (log   x)`=1/xlna

        a

                             3      

                         arctg   (log   x/x)            

                                    a            

    y`=arctg(log    x/x)+                     =1/xlna

               a              3

                  4     x                

    例3.设f(x)=3x     -e     +5cosx-1,求f`(x)及f`(0)

                         4       4                

    解:根据理论1可得(3x   )`=3(x   )`,(5cosx)`=5(cosx)`,  

    又,

       4      3                x      x                              

    (x    )`=4x    ,(cosx)`=-sinx,(e    )`=e    (1)`=0,

    故,

            4     x                        

    f`(x)=(3x    -e   +5cosx-1)`

         4      x                

    =(3x    )`-(e   )+(5cosx)`-(1)`

         3     x    

    =12x    -e    -5sinx

             3   x            

    f`(0)=(12x   -e   -5sinx)    =-1

                             x=0

                                          4  x                        

               4   x              arctg[(3x  -e  +5cosx-1)/x]        3  x

    y`=arctg[(3x   -e  +5cosx-1)/x]+                             =12x  -e  -5sinx

                                             3



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