使用help ,它上面说的很清楚啊!不知道你说的错误错在哪里? REDUCEM Reduce the number of points in vector data
[latout,lonout] = REDUCEM(latin,lonin) reduces the number of points in vector map data using the Douglas-Peucker line simplification algorithm. This method recursively subdivides a polygon until a run of points can be replaced by a straight line segment, with no point in that run deviating from the straight line by more than the tolerance. In this case the tolerance is computed automatically.
[latout,lonout] = REDUCEM(latin,lonin,tol) uses the provided tolerance. The units of the tolerance are degrees of arc on the surface of a sphere.
[latout,lonout,cerr] = REDUCEM(...) also returns a measure of the error introduced by the simplification. Cerr is the difference in the arc length of the original and reduced data, normalized by the original length.
[latout,lonout,cerr,tol] = REDUCEM(...) also returns the tolerance used in the reduction. Useful when the tolerance is computed automatically. 你再仔细的看看说明,不知道你到底哪里出错,所以也是无能为力啦!