用gnuplot画图

新疆大学学士学位论文0目录1.画平面图像.................................................................................................................................11.1直角坐标平面内画图.......................................................................................................11.1.1plot命令格式中各参数的说明..........................................................................11.1.2用plot命令在同一坐标内画多条图像.............................................................41.2用plot命令画参数方程确定的函数图像.....................................................................51.3用plot命令在极坐标画函数的图像.............................................................................61.4各种参数和选项的设置...................................................................................................71.4.1弧度制和角度制的转换.......................................................................................71.4.2自变量和因变量取值范围的设置.......................................................................71.4.3图例的位置...........................................................................................................81.4.4线的类型、粗细度、颜色等各种参数的设置...................................................81.4.5对坐标轴的设置.................................................................................................101.4.6添加直线和箭头.................................................................................................111.4.7图的大小和位置.................................................................................................132.画空间图象.................................................................................................................................162.1直角坐标空间内画图.....................................................................................................162.2各种参数和选项的设置.................................................................................................172.2.1设置网络线的数目..............................................................................................172.2.2自动调整坐标轴的刻度......................................................................................182.2.3沿z轴拉伸或缩小图象......................................................................................182.2.4对隐藏线的消除..................................................................................................192.2.5改变三维图的视角..............................................................................................202.2.6控制图象的弯曲部分..........................................................................................212.2.7给图象添加颜色..................................................................................................222.3画漂亮的彩色图..............................................................................................................23总结................................................................................................................................................25参考资料.........................................................................................................................................26致谢................................................................................................................................................27新疆大学学士学位论文11.画平面图像1.1直角坐标平面内画图一般在gnuplot中用plot命令来画直角坐标平面内的图形，它的命令格式如下：plot{ranges}{function|{datafile{datafile-modifiers}}}{axesaxes}{title-spec}{withstyle}{{definitions}function...}1.1.1plot命令格式中各参数的说明（1）选项ranges是自变量的取值范围（2）选项function指一个数学表达式或一对含参变量的数学表达式，表达式有可能完全地被定义，或者在一些gnuplot命令前定义。可以在plot中定义函数与参变量，只用逗号使它与其他项隔开。例1：想要画函数y=sinx,x∈[0,2]的图像plot[0:2*pi]sin(x)%自变量按弧度计算运行结果如图（1）所示图1函数y=sinx,x∈[0,2]的图像例2：想要画函数y=sin(Ax+),x∈[0,的图像plot[0:pi]f(x)=sin(x*a+b),a=2,b=pi/4,f(x)或者f(x)=sin(x*a+b)plot[0:pi],a=2,b=pi/4,f(x)运行结果如图（2）所示新疆大学学士学位论文2图2函数y=sin(2x+),x∈[0,]的图像（3）选项{datafile{datafile-modifiers}}根据已有的数据文件来作图时选用。例3：有文件“D:\gnuplot\test.txt”它的内容为-20.000000-6.083352-19.000000-6.072853…………………………..18.0000006.06119119.0000006.072853用此数据的一列为横坐标一列为纵坐标画图时要用如下命令即可。plot'D:\gnuplot\test.txt'运行结果如图（3）所示图3用已有数据画图（4）选项title表示图例例4：画标准正态分布密度函数2221)(xexf的图像且插入图例plot[-3:3]1/sqrt(2*pi)*exp(-x*x)title'DensityFunctionofTheStandardNormalDistribution'运行结果如图（4）所示新疆大学学士学位论文3图4插入图例(5)选项with表示函数图像线的类型、粗细度、颜色等各种参数格式：withstyle{{linestyle|lsline_style}|{{linetype|ltline_type}{linewidth|lwline_width}{linecolor|lccolorspec}{pointtype|ptpoint_type}{pointsize|pspoint_size}{fill|fsfillstyle}{nohidden3d|nocontours}{palette}}}例5：画函数xxxf)sin()(的图像plot[-2*pi:2*pi]sin(x)/xwithpointslinewidth3linecolor3或者plot[-2*pi:2*pi]sin(x)/xwplw3lc3运行结果如图（5）所示图5函数图像线的设置(1)例6：画函数xexfxsin)(的图像plot[-pi:4*pi]sin(x)*exp(x)withlineslinewith4linecolor2或者plot[-pi:4*pi]sin(x)*exp(x)wllw4lc2新疆大学学士学位论文4运行结果如图（6）所示图6函数图像线的设置(2)1.1.2用plot命令在同一坐标内画多条图像同一坐标内画多条曲线时，各曲线间均用逗号隔开就可以了。例7：同一坐标内画y=sinx，y=sinAx，y=sin(Ax+的图像plot[0:2*pi]sin(x)lw3lc2,sin(2*x)lw3lc3,sin(2*x+pi/6)lw3运行结果如图（7）所示图7同时画几条曲线图(A)图8同时画几条曲线图(B)新疆大学学士学位论文5例8：同一坐标内画函数y=x,y=x+a,y=a,y=3a和a=2的图像setxrange[-1:7]setyrange[1:7]a=2plotalw2,3*alw2,xlw2,x+alw2运行结果如图（8）所示1.2用plot命令画参数方程确定的函数图像默认情况下gnu