布置了一个题目，用一个算法计算以下函数的最大值

有没有啥网站能画出这种函数的图像的，或者能计算出这个函数的最大值的近似值，我做一个参考

安利wolfram

plot 20+x1*cos(x2)+x2*sin(x1) x1 from 0 to 10, x2 from -10 to 0 - Wolfram|Alpha Compute answers using Wolfram's breakthrough technology & knowledgebase, relied on by millions of students & professionals. For math, science, nutrition, history, geography, engineering, mathematics, linguistics, sports, finance, music… https://www.wolframalpha.com/input/?i=plot+20%2Bx1*cos%28x2%29%2Bx2*sin%28x1%29+x1+from+0+to+10%2C++x2+from+-10+to+0